Fig. 59.—Beginning to Make a Piece Mould.
3. Bed one end of the apple in damp sand, precisely as shown in the illustration (Fig. 59). If you have no sand, use fine sawdust, or wet corn meal. Some objects require clay. Do not have the sand wet and water soaked, for it will not yield so readily to the palette knife.
4. Dot a line on the sand all round, to show how far out to run the plaster, and avoid making the mould too thick.
5. Take two-thirds of a teacup of water, and put in plaster Paris until it becomes about as thick as New Orleans molasses. Stir thoroughly with a spoon, and let it stand two or three minutes.
6. Dip the plaster out with a teaspoon, and cover the exposed part of the apple. It will run down all over the horizontal surface of the sand, but never mind that. Make it cover the apple everywhere to a depth of a quarter of an inch. In some places it will be thicker. After about three or four minutes the plaster will be as stiff as modeling clay. While it is in this state take your palette knife and neatly smooth and shape the outer surface. Finish smoothing with the finger, and let the plaster harden. This will take about seven minutes longer, or until the plaster has warmed and cooled again. The time varies according to the humidity of the atmosphere.
7. Take the apple from the sand, with the half mould on it, wash off the sand, and neatly trim the edge of the mould with a knife.
8. With a blunt-pointed knife make three countersunk holes in the edge of the mould.
9. With a brush, anoint the edge of the mould with thin clay, clay-water, or soft soap, or lard oil, or even lard.
Fig. 60.—Second Step in Making a Piece Mould.
10. Turn the mould up on edge, and bed half of the exposed portion of the apple in the sand, as seen in Fig. 60. Fill in this space with plaster, precisely the same as when the first piece was made, which produces the second piece of the mould.
11. Make the countersunk holes in the edge of the second piece as before; fill in with plaster all the remaining space between pieces 1 and 2, and we have the third piece, which completes the mould. As soon as this hardens, tap the mould lightly all over with a small mallet, to loosen it from the object, then take out piece No. 3, and the mould is easily separated and the apple taken out. Take one part of gum sandarac (dissolved in ninety-five per cent alcohol) and three parts of white shellac, also dissolved, and mix them. They will form a solution a little thicker than water. Have the mould perfectly dry, and apply this solution to the entire inner surface of it with a small paint-brush. The solution will be absorbed at first, and you must continue to apply it until the inner surface has an egg-shell gloss, which is sufficient. Then oil the inside with lard oil.
Fig. 61.—Last Step in Making a Piece Mould.
12. Put together pieces 1 and 2 of the mould, cut a groove around them to hold a stout string, and tie it tightly to hold them together. Then mix some plaster, and fill each piece (1 and 2) about half full, walling it up the sides with the finger, aquarter of an inch thick, or as the plaster will make it. Then wipe off the exposed edges of the mould so they will fit snugly together with No. 3. Now mix up a little more plaster, about one-fourth the quantity first used, pour into the hollow, then put on the third piece; tie all tightly together, and turn the mould round and round slowly. This fills the third piece, and holds it in its place. Keep turning the mould slowly, and tapping it with the left hand. Leave a little of the plaster on the outside, on a piece of glass or paper, so that you can tell when it gets hard and flinty in the mould. Do not take off the mould until the cast is perfectly hard.
Fig. 62.—The Finished Mould.
How to Make a Waste Mould.—When a soft or fleshy object is to be cast, one which will yield, and draw out of the mould regardless of undercuts, a very quick and satisfactory process (provided a second copy of the cast will never be wanted) is to make what is called a waste mould. This, with a fleshy subject, is a short cut to a perfect cast, and often saves hours of valuable time. In obtaining casts of mammal heads, legs, or other parts, or casts of fishes and reptiles, it is the methodpar excellence. Let us learn the principles of it by making a waste mould and cast of a human hand.
1. Bed the hand in damp sand (i.e., one-half of it), as shown in the accompanying figure, No. 63.
Fig. 63.—The Beginning of a Waste Mould.
2. Give the exposed portion of the hand a good coat of lard oil.
3. Take two-thirds of a gill of water in a teacup, put into it half a teaspoonful of dry Indian red (to be bought for five cents at any paint store), and mix it up. This is to color some plaster with which to make a thin, colored lining for our mould, the purpose of which will be appreciated later on.
4. Mix with this red water one and one-half gills of plaster Paris, stir it up thoroughly to get it well mixed and free from air-bubbles, then with a teaspoon distribute it all over the hand until it is completely covered with a coat of the pink plaster about one-eighth of an inch thick.
5. After this thin coat has hardened, anoint the surface of it with lard oil or clay water, so that the plaster which is to be put upon it will not stick to it, but separate readily when the outer case of the mould is chiseled off.
6. Take one and one-half gills of water, and three-quarters of a pint of plaster, mix for outer case of mould, and apply on top of the pink lining to a thickness of about half an inch. Let this get perfectly hard. (Fig. 64.)
Fig.64—Second Step in Making a Waste Mold.
7. Take the subject out of the sand. Turn it over, anoint the edge of the mould with clay water or lard oil, and treat the other side in precisely the same manner. This is the course when the whole object is to be cast. If half the object is sufficient, as is the case in taking a record cast of one side of an animal's head and body, then take the subject from the mould, and
8. Wash the inside of the mould thoroughly to get out the clay and sand.
9. Anoint the inside of the mould with clay water, thin clay, or lard oil, and lay it in position to receive the plaster.
10. Mix a proper quantity of plaster, pour it into the mould and let it harden.
Lay the mould (with the cast inside) on a cushion, or on your lap; take a half-inch chisel and a light mallet, and, beginning at the end nearest your left hand, chisel away the case of the mould, bit by bit, until you come down to the pink lining coat, which shows that you are close to the cast.Great care is necessary to avoid breaking the cast, which of course is very easily cut or broken. In cutting off the pink lining be exceedingly careful not to go too deep (Fig. 65). The purpose of this lining is to show you when you are close to the cast. If the case of the mould is quite thick, hold the chisel on a slant of about fifty degrees from a perpendicular, and pare off the upper surface gradually.
Fig. 65.—Chiseling off the Waste Mould.
Making Gelatine Moulds.—There are many objects which can not be copied in plaster by either of the above methods without great difficulty. These are hard substances, the surfaces of which are extremely irregular and full of little hollows, such as meteorites, statuettes, sculptured rocks, or models such as those of the Aztec calendar stone and sacrificial stone. When a number of copies are required, the making of a waste mould for each copy is out of the question, and the manufacture of a piece mould that will draw off is also a long task, to say nothing of making the casts themselves and cleaning them up. The solution of all such difficulties is the gelatine or "glue" mould, which is elastic, pliant, and yet keeps its shape perfectly. This is how to make it:
Let us suppose we are to make a gelatine mould of a flattened meteorite, eight inches in diameter and about three inches thick. Take some potter's clay, or modeling clay, which has been nicely worked up in a square lump, and is not wet enoughto be too sticky. With a small wire, cut it into slabs about three-quarters of an inch thick, and with these cover the entire object to the depth mentioned. Put the clay on everywhere the same thickness, making it conform to the irregularities of the surface. This clay will presently be exactly replaced with gelatine.
Having coated the object as described, make a plaster Paris mould of the whole of it, in two parts, which separate horizontally around the outermost edge. When you make a plaster mould of the upper half, erect a high cone of clay over the centre of the meteorite as it lies flat upon the table, so that it will make a funnel-shaped hole in the upper half of the mould, through which you can pour in the gelatine. Of course the two pieces of this plaster mould must fit nicely together, with countersunk holes. This plaster mould of the clay-covered object is called the "jacket," and its use will soon be apparent. Now for the gelatine.
Recipe for Gelatine Moulds.—The gelatine compound is made by taking glue and glycerine in the following proportions, varying the quantity to suit the size of the object: Of best Irish glue, 3 pounds; glycerine, 1-1/4 pounds; and about 1-1/2 ounces of white-wax. Dip the glue in water, and then roll it up over night in several thicknesses of wet cloth, so as to soften it without soaking it in water, which is an element to be kept out. In the morning the glue will be soft. Procure a large-sized gluepot, or improvise one by putting a small tin pail in a larger one, with water between, and in this put the glue and glycerine and cook it up. Melt the wax separately, and pour it in after the other is well mixed and hot. A gelatine mould can be made of any degree of hardness by adding dry white zinc which has been carefully ground in a mortar, but ordinarily none is necessary.
To make the gelatine mould the clay must all be taken off the object, and the latter washed clean. Lay the lower half of the "jacket" upon the table, inside uppermost, and drive four small wire nails into it at different points, allowing each one to project just three-fourths of an inch, for the meteorite to rest upon, and give space for the gelatine to flow underneath and form that part of the mould. Now put the meteorite carefully inplace, resting on these nail-heads, and then put on the upper half of the "jacket." Cord the jacket tightly together without disturbing the position of the object inside. If there are any cracks at the edges, fill them up with clay. Now pour in the hot gelatine at the funnel-shaped hole in the upper half of the jacket, until the mould is quite full. Let the mould stand two hours to cool and harden; then remove the upper half of the "jacket." To get the object out, take a sharp knife and slit the coating of gelatine fully half-way round, so that the two halves can be opened like an oyster, and the object lifted out. The inside of the gelatine mould must now have a coating to make it impervious to the water in the plaster Paris.
Mix up the following:
1 teacupful of spirits of turpentine.About 4 level teaspoonfuls of white lead.About 1 teaspoonful of lightning dryer.Mix this well, paint the inside of the mould with it, two coats, which makes the gelatine waterproof.
Mix this well, paint the inside of the mould with it, two coats, which makes the gelatine waterproof.
To make a cast, oil the inside of the mould with lard oil, put the plaster jacket around it, so that it fits perfectly, and tie the two pieces of the jacket firmly together to prevent a disaster when the plaster begins to heat in the mould.
Mix your plaster with ice-water for the same reason, and you will have no trouble. For irregular objects, the working of a gelatine mould is perfection itself. It yields gracefully in coming out of the undercuts and around corners, takes every detail perfectly, and in the jacket its shape is always the same. A careful operator can make from twenty to fifty copies of a cast in a single mould before its loss of sharpness necessitates its abandonment.
Casting Parts of Mammals in the Flesh.—Although it isusually impossible to carry more than ten or fifteen pounds of plaster into the field when you go off on a collecting trip, a quantity sufficient for a special purpose is often worth its weight in silver dollars. But many a fine subject comes entire to the laboratory, where the taxidermist can work his will upon it. If I have never done any other good thing in my life, I believe I have at least taught some of our best American taxidermists the usefulness and value of plaster casts taken from the flesh. It is only a few hours' work to make a mould and cast of the entire side of an animal as large as a large dog, or even a lion, and still less to take half the head, or the nose, a fore leg, or hind leg. Once we had an opportunity to cast the entire head of an immense bull moose, and right greedily did we seize it. The resultant cast has been of priceless value to us as an exact record of the form of a wonderful head. If you wish to do a fine piece of work, and have the animal in the flesh, by all means make a cast of one whole side of it. It will repay its cost ten times over. No record of form is equal to a cast, even though it be a poor one. I once made a mould of one entire side of the head of a large leopard in twenty minutes. It is about an hour's work to make a good mould of the entire head of a monkey, or two legs of a tiger.
The principles of this work have already been stated, and there is little more to be said. If the specimen is a large one, lay it upon the floor, build up around it with sand, or even wet sawdust, and arrange to take one side of the animal's head, or entire form, as the case may be. To take the two legs it will be necessary to first fill plaster under each one to make a separatepiece. In order to keep the plaster from sticking to the hair, fill the hair full of thick clay-water, or thin clay, and plaster it down with the pasty mass so that the plaster Paris will not run into it. Coat the whiskers and eyelids with warm wax, or fill them full of clay. Do this thoroughly, to save the hair and save trouble. A little hair will stick in the mould anyway, but when you take the mould off, work the animal slowly and carefully from the mould, perhaps pouring in a little water to facilitate matters.
Always make a waste mould in these cases, to save time. If your cast breaks in two while you are chiseling the mould off, go ahead more carefully, and when you are done, chip the broken edges at the back, wet them with water, and stick them together with plaster. Small casts can be stuck together with shellac. If your mould breaks in pieces while you are taking it off, don't be discouraged, but simply put the pieces together, back them up with more plaster, and come up smiling for the next round.
It is often necessary to cast skulls or teeth, to put in skins that are being mounted, though it is better to carve a skull out of soft wood.
Casting Fishes.—Fishes are easy and interesting subjects to cast.
Usually only one side is taken, and the cast is then mounted on a flat slab, or perhaps on two brass standards. The full method of procedure is as follows:
Wash off the mucus with alum-water. Put some dry alum on the side to be cast, to harden the soft edges of the fins, and make every scale stand out distinctly. Clean the fish carefully, close the mouth, adjust the eye and the gills. Lay the fish on its side, with the side to be cast uppermost. Take some modeling clay, beat it out, and roll it into a smooth, square cake with parallel sides. With a small wire cut a section of this cake, and place it under each fin, so that the fin will be held in position as in life.
To make a piece mould, make it in three pieces, thus: Put up a wall of clay around the head from the base of the dorsal fin to the base of the anal fin, keeping the clay wall a little distance away from the head and body. With plaster Paris fillin the space thus left, up to the median line of the fish, but no higher.
With a knife work the plaster under the edge of the fish, and let it harden; then put two countersinks in each side. For the main piece, mix some dry color in enough plaster to coat the fish one-eighth of an inch thick, make it thin, and pour over with a spoon. When covered thinly, blow hard upon it, all over, to make it take the scales sharply; then put on enough more to make the colored coat an eighth of an inch thick. Let this harden, then put on the thick coat of white plaster, which is to be chiseled off, as this is supposed to be a waste mould. In making the cast, if it be possible make it before the mould gets dry, so that the latter will chisel off easily. Pour the mould nearly full of plaster, then set a piece of wood in at the back to afford a means of screwing the cast to a panel, or inserting standards. After the cast is made it must, of course, be carefully painted, which is another matter, and is treated elsewhere.
Casting Reptiles.—After all the detailed directions that have been already given on this subject it is not necessary to speak further of methods. Mr. Joseph Palmer, of the National Museum, has produced such pleasing and artistic representations of reptiles of all sorts, especially serpents and tortoises, it would seem that perfection in this line has been reached. His serpents are all on imitation rocks, trees, or earth, and in about all the attitudes they would assume in life. They are represented as crawling, sleeping, fighting, striking, and threatening. By the introduction of wires in the moulds while making the casts, they are made to act quite naturally. Of course they have been carefully and artistically painted, and half the credit for their beauty is therefore due to the colorist. Lizards of many species, large and small, and also tortoises and turtles of every American species, are thus represented with great success. This interesting collection is well worthy of study; but to the taxidermist who is not also a first-rate artist in oil colors, this method is beyond his powers.
Itis really strange that so few American collectors are taughtthe scientific value of skeletons, and the need to collect them, especially when in the haunts of rare animals. While hundreds of collectors gather bird skins by the cord, perhaps not one out of the whole lot saves a rough skeleton. Any one who is wholly unaccustomed to the preparation of skeletons is apt to stand appalled at the thought of preparing one from the beginning; and, indeed, thefinalwork of cleaning and mounting is no child's play. But let me assure you that, so far as the field work is concerned, you can easily become a successful collector of skeletons of all kinds, even though you may never learn to clean and mount one. All you have to do in the field is to "rough out" skeletons from the flesh, and dry them in compact bundles for shipment.
A Rough Skeletonof a mammal, bird, reptile, or fish, is simply the complete bony framework of the body, from which the most of the flesh has been cut away with a common knife, after which the skeleton and remaining flesh has been dried preparatory to its being, at some indefinite time in the future, taken in hand by a professional osteologist. The work of preparation on such specimens is very simple, and when once learned is easily performed.
Selection of Specimens.—When a choice is possible, select large and perfect adult male specimens as subjects to be skeletonized. The skeletons of young animals are always imperfectin development, do not properly represent a species, and are seldom valuable except for comparison with other specimens of the same species. Very often a fine adult specimen has its skin so badly torn by shot or bullets, or the skin covering is in such a bad state of shedding, moulting, and the like, that the skin is totally unfit for preservation. In such a case the preservation of a fine perfect skeleton becomes a clear gain of one specimen to the collector and to science.
A perfect skeleton is one in which not a bone is missing, and in which no substitutions have been made. But it is by no means always possible to secure a wild animal without breaking some portion of its osteological anatomy. When a bone is broken, the best thing to do is to supply it with a corresponding bone from an animal of similar size and age. Sometimes the closet naturalist, who generally thinks that rare wild animals are gathered like berries, will grumble because a broken bone has thus been replaced, and find fault with the size of the substitute, but that need not trouble the collector's conscience in the least. I once shot a fine prong-horn antelope buck, skeletonized it carefully, cut up the skeleton, and carried the whole of it for three days attached to my saddle, while I rode a very restive and dangerous horse, and also carried two blankets and a Maynard rifle. That skeleton, thus earned, had some broken bones supplied from another specimen. It finally went to Europe, and fell into the hands of a closet naturalist, who blithely found fault with the collector because of the supplied bones. Again, when I once risked drowning in order to enter a cave on a dangerous sea-coast to collect guacharo birds, and got a goodly number, a German closet naturalist complained bitterly because a skin that was sent to him had two missing tail-feathers supplied by two other feathers that were a trifle smaller than the missing ones.
But I did once perform a feat in South America which filled the souls of my friends at Ward's with wonder, and even admiration. In collecting about half a dozen skeletons of capybara, each of which I took care should be absolutely perfect, by some brilliant man[oe]uvre I contrived to send home to the establishment one skeleton which was the happy possessor of two left forelegs and two left hind legs, but never a right one; and inthe language of the Old Testament, "his bones are there to this day!"
Skeletons of Mammals: Small Objects.—The smallest quadrupeds—such as bats, small rodents, shrews, and the like—should be eviscerated, and preserved in alcohol, without being skinned; but each specimen should be fully labeled. As a general thing it is best, for various reasons, not to dry such small carcasses.
For all mammals below the size of the Virginia deer, proceed as follows:
1. Remove the skin as expeditiously as possible, in order to have a fair show at the skeleton.
2. If the skeleton issmallerthan a fox, leave the legs attached to the body, for convenience, until you have cut the flesh away from them with your scalpel or pocket-knife, without any disjointing. When all the legs have been thus roughly denuded of flesh, cut them loose from the body and lay aside for the moment.
3. If the specimen is larger than a fox, cut off the legs from the body, lay each one flat upon the ground, inside uppermost, divide the flesh all the way along it directly over the bones, and literally dissect the bones out of the mass of flesh, instead of cutting the flesh away piece by piece. This is the quickest and neatest way. The scapula must come off with the fore leg, and be left attached to the humerus. Be sure you cut off all the masses of flesh,but don't cut off the knee-pan, as you may easily do if you are not watchful.
4. Now for the carcass. Hold it on its back, begin at the breastbone, flake off the flesh from the sides of the body close down to the ribs, until the backbone is reached. Cut off as much flesh as you can (hurriedly) from along the backbone.
5. Next attack the abdomen. Beginning at the lower point of the breastbone, detach the walls of the abdomen from the ends of the short ribs, down to the lumbar vertebræ, and so on around the iliac margin of the pelvis. Cut through the diaphragm close up to where it is attached to the ribs, and remove at one effort the entrails and vital organs.
6. Cut away the flesh from the pelvis, both inside and out, and the flesh of the tenderloin from underneath the lumbar vertebræ.
7. Cut the flesh from the thick portion of the tail.
8. Cut off the head at the first cervical vertebra, and clean the skull as previously described elsewhere, but leavethe hyoid bone in its place.
9. Cut the flesh away from the neck vertebræ as well as you can. Be careful not to cut the sternum (or breastbone), which is soft cartilage, and easily cut; nor the ends of any vertebral processes, nor any soft bones.
10. If the skeleton is a small one, it is apt to get quite bloody during the operation. Wash it clean, and if necessary soak it in clear water for an hour or two. It will come all the whiter for it in the end. Skeletons of ruminant animals are generally clean enough without that.
11. Do not poison a rough skeleton with arsenical soap, nor put salt upon it; so says Mr. Lucas, the osteologist of the National Museum. The former has a tendency to prevent skeletons from properly macerating and coming white. Sprinkle dry arsenic upon a skeleton, if anything is necessary to protect it fromDermestesand other insects. Never put alum on a skeleton.
Fig. 66.—Rough Skeleton of a Small Animal. (After F.A. Lucas.)
12. The last thing is to make up the skeleton into a small, compact bundle, that will pack nicely and economically when dry, and withstand some pressure without breakage. Put the skull in the chest cavity. Fold up the upper joints of the legs, put the foot of each in the pelvis, and the other end in the cavity of the chest. Now tie all the legs tightly to the spinal column. (See Fig. 66.) Bend the tail under the pelvis and tie it fast also. Finally, hang the specimen up in the shade and wind, so that it will dry quickly.
It will be observed that the above process leaves the body ofthe skeleton entire, and all the bones of each leg and foot united by their natural ligaments. A skeleton prepared thus may ultimately be mounted as a "ligamentary skeleton," or it may be disjointed throughout, macerated, and mounted as a "disarticulate skeleton." Except for skeletons of bison, elk, and other animals which are entirely too large to admit of transporting their bodies whole, it is much the best to prepare all others in the field as described above, and disarticulate some of them afterward; for this reduces to a minimum the chance of losing some of the parts.
Skeletons of Large Mammals.—The process of roughing out the skeletons of large mammals, no matter how large they may be, is precisely the same as described above for small ones; but to make it possible to transport and box them, they must be cut to pieces, or, I had better say,disjointed, for fear some zealous partisan might interpret my words too literally, and go at a valuable skeleton with an axe. And right here let me publish a law which is as fixed and unalterable as the laws of the Medes and Persians, and admits of no exception:
In disarticulating a large skeleton, no matter how large, an axe or hatchet must never be used for any purpose whatever.Use nothing but the knife, and in a few cases a small saw to separate the sternum from the ends of the ribs.
To come down to the details of cutting up a large skeleton in, the field, and making it up into a number of separate bundles, let us suppose that the skeleton lies before us, completely roughed out, in accordance with previous advice. The bones of each leg must be dislocated (at the "knees" in ruminant animals) either once or twice, so that the parts can be easily handled. In a full-grown elephant the leg bones are so large it is necessary to cut the ligaments at each joint, so that the scapula, humerus, radius and ulna, and foot may each be handled separately.
Of course, the head is to be cut off at the first cervical vertebra. Then, by careful work, and much coaxing with the sharp point of the knife, dislocate the spinal column just where the neck joins the body. At first this will bother you, but have patience and you will soon learn how to do it easily and quickly. In dislocating the spinal column, take hold of the neck, move itbackward and forward, and strain it a bit to see just where the articulating surfaces of the vertebral process are, so that you can cut them. When your intelligence has made some headway on the joint, then you may put forth a little main strength and tear the vertebræ apart, but do not attempt this too soon.
The next thing is to cut off the ribs, and the first step toward this is to cut out the sternum, or breastbone. (See Plate XX.) This so-called bone is really cartilage, soft enough in a fresh skeleton to cut on the outside, and in thin places, like cheese rind. It must be cut out in one piece, the same as may be seen in the figure of the mounted skeleton, and the dotted lineA Bshows where the cartilaginous ribs of the sternum join the bony ribs that form the main arch of the thorax. At the points marked by the dotted line, cut the two apart. I have never found it necessary to use a saw for this work in a perfectly fresh skeleton, but in dry ones a saw is necessary. When you come to the short, or "floating ribs," as they are called, it will be found that their cartilages are only attached weakly to the cartilages of the previous ribs, or else are altogether free. These must be cut from the ribs and preserved with great care.
After the ribs have been cut free from the sternum, separate them from the backbone, one by one, make them up into bundles, and tie them up. The pelvis is to be separated from the spinal column at the last lumbar vertebra; and if necessary the spinal column may be again dislocated about the middle.
Formerly it was my practice to poison all rough skeletons with a thin wash of arsenical soap, to make them dry without smelling badly, and to keep off the myriads of insects that the shreds of flesh would naturally attract. Now, however, in obedience to the mandates of Mr. Lucas, I have eschewed the use of arsenical soap for this purpose, and recommend the use of dry arsenic instead, which does not retard the cleaning of the bones.
Rough Skeletons of Birds.—As in the case of a small mammal, first remove the skin from the body; but if the identity of the bird is in doubt, leave the large tail feathers and the primaries in place, for future reference. In fact, it is a good plan to always leave the primaries and spurious quills on the wing, for then there will be no danger that some of the small bonesof the last joint will get lost or cut away by mistake. Moreover, when you come to tie up the skeleton, the primaries will afford valuable protection to the ribs.
Fig. 67.—Rough Skeleton of a Bird. (After F.A. Lucas.)
With a bird, the entire skeleton should be roughed out before any disjointing is done, and even then none is necessary, save to cut off the legs of large birds, especially those with long legs. Study carefully the accompanying figure of a bird skeleton (Fig. 67), and then it will be hardly necessary to say more than to roughly, but carefully, cut off the flesh with a cartilage knife or scalpel, and remove all the viscera. Look out for those delicate little points on the neck vertebræ, and also be very careful not to cut off those curious little appendages (called uncinate processes) that project backward from the middle of each rib. Leave the hyoid bone in its place, and also the bony ring surrounding the eyeball of the great blue heron, the owl, and other birds of prey. If any portion of the windpipe reveals any bony structure, the entire windpipe should be saved. Whenever any tendons are found to be partly ossified, as they will certainly prove to be in the "drumstick" of your Thanksgiving turkey, leave them in place for the osteologist to do with as he pleases.
When in doubt about any special part, give the osteologist the benefit of the doubt by saving the special part for him.
If the bird is a large one, cut off the head, and after cleaning it pack it away in the chest cavity. If the bird is small, you can leave it attached to the neck, and remove the brain by bending the head down and cutting it half off from above, thus exposing the occipital opening at the back of the skull, through which the brain may be drawn out.
After the skeleton has been roughed out, it should always be cleaned by washing it in a basin of water and brushing it meanwhile with a soft tooth-brush. If blood is left on the skeleton, the bones will absorb it, and become permanently discolored thereby. The cleansing done, make the skeleton up into a compact bundle by folding the wings naturally against the body, bending the neck down in some way so that it can be tied upon the body, and either cutting off the legs and putting them into the thorax and pelvis, or leaving them on and folding them up as compactly as possible. Then tie the bundle up thoroughly by passing a light string many times around it, so that it can never lose its compactness. Sprinkle it with dry arsenic, or wash over withthinarsenical soap, and hang it up in the shade to dry.
Skeletons of Reptiles.—After all the foregoing directions, it surely is unnecessary to describe, in detail, the skeletonizing of reptiles. The principles are precisely the same as already set forth for birds and mammals. Wherever special bones or cartilages are found, as in the abdominal-cartilaginous ribs of crocodilians and certain lizards, they must be carefully saved whole andin situ. With large skeletons, take whatever means are necessary to get them, while fresh, into compact shape for drying and packing. With large crocodiles and alligators, the neck, legs, head, and tail all go nicely inside the body, as I have proved scores of times. The skeleton of a large serpent is easily done up in a close coil, by which it not only takes compact shape, but the ribs are well protected. With serpents, do not attempt to cut the flesh from between the ribs, for it is desirable that it should remain.
On each rib of a crocodilian there is a strange, flat piece of cartilage attached to the posterior edge at the middle of the rib, and projecting backward, quite overlapping the next rib, as sure as the world the reptilian development of what in the full-fledged bird becomes a bony uncinate process. You will soon discover this in skeletonizing your first crocodilian, and be sure to respect its anatomy.
It surely is superfluous to say that every skeleton must be carefully and fully labeled, and in a substantial way.
Fishes.—This subject has been treated in Chapter IX. (Collecting Fishes).
Skeletonizing Cetaceans.—The rough skeleton of a cetacean—porpoise, blackfish, whale, and the like—is the bloodiest, greasiest, nastiest specimen the collector ever has to prepare. Nevertheless, they are necessary evils, and fortunately their structure is so simple that their roughing out is not a difficult matter. The vertebral column terminates in a point, there being no bones in the flukes of the tail, or the dorsal fin. The best way to operate is to split the body open along the middle of the back all the way from head to tail, and carve the flesh away until you reach the vertebral column, and after that the ribs.
The vertebral column must be cut in two in two or more places, according to its size. Midway between the last pair of ribs and the tail, and underneath the vertebral column, lie two very useless and absurd little ossifications known as the pelvic bones. They are called pelvic bones because that happens to be a handy name. They bear about as much resemblance to a genuine pelvis as a cigarette does to a locomotive. They are so small that it takes an expert with a search-warrant to find them, and, for my part, I always consider their loss a real gain to the cause of science. Of course the scapula and flipper, the ribs and the sternum, must each in turn be cut away, cleaned as well as possible, and bundled up to go with the head and the three sections of the vertebral column.
Packing Skeletons.—All rough skeletons, skulls, etc. (as well as all skins) must be thoroughly dry when packed, or they will sweat, soften up, smell offensively, and spoil any dry skins, or other perishable objects that may be packed with them. Skeletons should always be packed in tight boxes, so that rats and mice cannot get into them and gnaw the small bones. Tie some soft material over the teeth of separate skulls to save them from getting broken. Put the largest skeletons and skulls at the bottom, and use hay, straw, or excelsior for filling. Of course the small and fragile specimens will be put in the protected corners and crevices between the larger objects, and, as before remarked, dry skeletons that have been made up into compact bundles will stand a very considerable amount of pressure without breaking.
Collecting Fossil Skeletons.—The vertebrate zoologist glories in the skeleton of almost any living species of vertebrate, but a fossil skeleton he fairly worships. The more of previous theories it upsets, the dearer it is. If it is a reptile with feathers on its tail, a bird with teeth, or a scientific what-is-it, as was the gigantic megatherium, it is simply canonized. Beware, then, red-handed hunter of living species, how you recklessly pass by a bit of bone protruding from a "cut bank" beside some stream, for you know not the day and the hour when you may touch elbows with His Mysterious Highness, the Missing Link.
The tertiary deposits of the United States contain the fossil remains of many magnificent vertebrates, impossible even to mention here. Very often huge bones and tusks of the mastodon are unearthed in well or ditch digging, and before they receive proper attention are exposed to the air and allowed to crumble into dust in a few hours. If a fossil bone is very soft when dug up, it will crumble in a short time unless properly cared for. If this is likely to be its fate, cover it up again without delay, to keep the air from it until you are ready to preserve it. To accomplish this, prepare a kettle of glue water (simply hot water with a little glue dissolved in it) and wrap the bone tightly from end to end with an abundance of twine. Then with a ladle or large spoon pour the glue water over the bone or tusk, gradually, but continuously, so that it will soak in, and when dry, it will bind together the weak material and form a hard shell of some thickness and protect the form of the bone intact. This will often save a fossil which would otherwise fall into countless tiny fragments in a few hours.
If a skeleton or portion thereof is embedded in a matrix of hard rock, do not attempt to work it out fully in the field. That is work for the laboratory—and a very good one at that, sometimes requiring costly tools, much skill, and plenty of time to chip away the surrounding rock.
Oftentimes the fossil remains of a fish, small reptile, or mammal are uncovered bodily by the removal of the slab of rock which has covered it for ages, like a blanket. In such cases do not attempt to pick the bones, one by one, out of their resting-place, but procure the necessary tools, cut out the entireslab of rock which contains the skeleton, and keep it in one piece forever. Such specimens have a good market value in cash, which will well repay the care and labor bestowed upon them; but at the same time a novice should not make the very common mistake of supposing that a fossil which is newto himmust necessarily be worth its weight in gold. If you wish to sell any good fossils, you will get a fair valuation by offering them to Professor Henry A. Ward, Rochester, N.Y.
Thereare two ways to clean the skeletons of large mammals:(1) by boiling the bones, and (2) by maceration. The first is short, cleanly, and agreeable; but the skeleton produced by it is sure to be full of grease, and is anything but white and pleasing to look upon when mounted. The boiling process is also detrimental to the texture of the bone. The professional osteologist, to whom a greasy bone in a mounted skeleton is an unpardonable offence, never thinks of boiling a skeleton to get the flesh off, for the reason that the grease is boiledintothe bone instead of out of it. Cleaning by boiling is permissible only under exceptional circumstances. If you wish a particular skeleton for a special purpose within a very short time, or if you are so situated that macerating a skeleton is impossible then boiling is excusable, butsteamingis far preferable.
Preparing a Skeleton for Maceration.—It is, of course, to be understood that it is only the skeletons that are too large to be scraped and mounted as "ligamentous skeletons" that are to be macerated, bleached, and afterward articulated with wire. The first thing to do is to cut out the sternum in one piece, as already shown in Plate XXI., poison it in arsenic water, and hang it away to dry and be scraped afterward. A sternum must never be macerated, for it is so soft the cartilaginous framework would be entirely destroyed. The skeleton must now be cut completely to pieces, excepting that it is not necessary to separate all the vertebræ of the spinal column. The ribs must be cut off, and the joints of the legs cut asunder. The large bones of the legs contain marrow, and of these bones each one must have a large hole drilled in each end on the face of the articulating surface, so that when mounted the holes will not show. These holes are to afford the water access to the interior of the bone.
Macerating and Cleaning.—The maceration of a skeleton is a question of time as compared with eternity. Procure a wooden barrel or keg large enough to contain the entire skeleton, knock the head out and see that there are no nails, nor any other metal anywhere on the inside to stain and discolor the bones. Pack the skeleton closely in the empty barrel, fill it up with water and let it stand. In a few days its offence, like Othello's, "is rank, and smells to heaven." But that is no matter, provided your barrel has no neighbors. Let it stand for four months, six months, a year, or two years if need be, until every particle of fleshy matter on the bones has disintegrated and become a pulp. Keep the barrel covered, and when the water evaporates and the bones on top are about to be exposed, fill up with water and keep the bones always covered. If a skeleton is very bloody, it is well to soak it for a week in salt water to dissolve the blood-corpuscles. Then it may be macerated as directed above. The odor will be horrible, but if you are going to study bones you must not mind that.
When you find upon examining the bones that the flesh has totally disappeared from them, leaving them dark-colored or even black, but without any fleshy matter upon them, they are then to be taken out. Pour off the water, place the entire contents of the barrel in a large sieve-bottomed tray, and wash the bones thoroughly. When that has been done, put them in a large tub of boiling water, and keep them in warm water while you scrape all the bones, one by one, with your bone-scraper, and scrub them with a stiff brush, going over the entire surface, and washing them meanwhile in the warm water. The interior of each of the large leg bones must be washed out with a strong syringe, and every cavity in the vertebræ must be carefully scraped out.
Bleaching.—Having carefully scraped and washed the bones, the entire skeleton is now to be soaked for a short time, the length of time varying according to the size and age of the skeleton, in a solution of chloride of lime and water. To make this of the proper strength, dissolve about two or three ounces of chloride of lime in a barrel of water. Bones of young or immature animals must not be left in this solution as long as those of old specimens. Young bones are soft and porous, andthe chloride of lime will soon destroy them if they remain in it too long.
The following skeletons, adult in every case, require to be left in this solution a length of time as stated herewith: Dog, 6 hours; sheep, 6 hours; deer, 8; buffalo, 12; elephant, 12.
After removing the bones from this bath, wash them with clear water, lay them in slat-bottomed trays, with cheese-cloth above the slats, without piling one bone upon another, and expose them a number of days in the hot sun. After they have bleached on the upper side, turn them over. If it does not rain upon them occasionally, they should be sprinkled with water, late in the evening or early in the morning, to hasten the process.
Great care is necessary to keep the tiny carpal, tarsal, and phalangeal bones from getting lost. When the bones are white as chalk, or nearly so, tie the parts of each skeleton in a stout paper bag by itself, label it, and put it away until you are ready to mount it.
The sternum is to be soaked in clear water, with a little washing soda to cut the grease, until it is soft, and then scraped the same as the bones of a ligamentary skeleton, which process will be described in the next chapter.
Theskeletons of small vertebrates should never be maceratedprevious to mounting, for the reason that their complete rearticulation would be a practical impossibility. The bones must be left united at the joints by their natural ligaments, which when dry become quite hard, and with the aid of either one or two small brass standards will hold the entire skeleton erect and in proper shape. Skeletons mounted thus, with the parts attached to each other by their own dried ligaments instead of wires, are called ligamentous, or ligamentary, skeletons. All mammals smaller than a large fox, all birds smaller than a small ostrich, all turtles, lizards, iguanas, serpents, crocodilians, and all fishes are mounted in this way. Fortunately it is possible to clean to perfect whiteness the skeletons of almost all these subjects without putting them through the maceration process, which resolves everything into its component parts.
Drying before Mounting.—In order to have a skeleton so that it will scrape to the best advantage and become as white as possible, every ligamentary skeleton must be dried before it is finally cleaned and mounted. In a perfectly fresh skeleton the epiphyses and ligaments are so soft the operator would find it hard to keep from destroying them with his keen-edged steel scrapers, and the smaller bones and cartilaginous members would also be in great danger of mutilation in the same way. When a skeleton dries, all these soft portions harden, and when afterward the skeleton is soaked in clear water for two or three days, or longer as may be necessary, the flesh quickly softens so that you can scrape it all away without encroaching on the framework, and the ligaments at the joints are just soft enough that a portion of it may be scraped or trimmed away, and yet leave sufficient to hold each joint together.
Relaxing a Dry Skeleton.—As intimated above, this is accomplished simply by soaking the specimen in clear water until its joints are pliable, and the flesh upon the bones is soft enough to scrape off. In order that the specimen should not become offensive and disagreeable to work upon, it must not soak long enough for decomposition to set in, for that is the first stage of maceration. Therefore, scraping should begin just as soon as the flesh is soft enough to be readily removed.