FIG. 86.
That human jaws, like human ears, are degenerating is demonstrable by actual measurements.Mummery, who examined the skulls of 200 Briton and Roman soldiers, found the narrowest 2·12 inches, the highest 2·62, with an average of 2·50. The width of jaws of 402 British soldiers to-day is: narrowest, 1·88; widest, 2·63; average 2·28. The highest width was very rare; only eight measured 2·50. The jaws of the mound builders, compared with the existing cliff dwellers, show similar results. The average width is about 2·50 inches. This is also true of nearly pure negro races. Measurements of normal jaws of 855 Italians of Central Italy were: narrowest, 1·88; widest, 2·63; average 2·17. Measurements of normal jaws of 4,935 Americans gave the following results: narrowest, 1·75; widest, only one case, 2·56; average 2·13. If in the highest type of physical man the width of the upper jaw from the outer surface of the permanent molars near the gum margin was originally 2·50 inches in diameter, the jaw of people now living in the same locality is from 0·25 to 0·33 inches smaller. Although the jaw has thus been growing smaller, since there are no breaks or deformities in the contour of the dental arch this must be regarded simply as an adaptation to environment, and not degeneracy in the proper sense of the term. The degeneracy of the jaws, on which I would lay special stress, is that in which deformityhas resulted from inability to adjust structure to a changing environment. When arrest of development so takes place that deformities of the dental arch result, the jaws vary from two inches to one inch in width. As a rule, the teeth are the same size to-day that they were thousands of years ago. This is due to the fact that they are ante-natal and not influenced by post-natal systemic changes. The jaws do not contract as a result of mouth breathing.[218]If the jaw be arrested and be smaller in circumference than the teeth, a break takes place in the dental arch and deformity results. Two types of deformity occur, the V-shaped arch and the saddle arch. All other types of deformity, not due to local causes, are modifications of these two. These deformities always occur with the second teeth only. In these cases the facial profile assumes the perpendicular line or arrested face, as illustrated in the chapter on Degeneracy of the Face. They are never seen before the sixth year, when the second set begin to erupt and are complete with development of the second molars at 12. They may become exaggerated later in life from want of room, the eruption of the third molar and want of harmony in relation of the two jaws when closed.
FIG. 90.
There are three characteristics of the normal arch. Independent of temperamental peculiarities, the line extending from one cuspid to the other should be an arc of a circle, not an angle or straight line; the lines from the cuspids to the third molar should be straight, curving neither in nor out, the sides not approximating parallel lines. Absolute bilateral uniformity is not implied in this, as the two sides of the human jaw are rarely, if ever, wholly alike. A uniform arch necessitates uniformity of development between the arch of the maxilla and the arch of the teeth and a correct position of the individual teeth in their relation to each other. When there is inharmonious development between the jaws and the teeth, as may happen when one parent has a small maxilla with correspondingly small teeth, and the other a large one, with correspondingly large teeth,if the child inherit the jaw of one and the teeth of the other, irregularities must follow. Such difference in diameter between the arch of the maxilla and that of the crowns of the teeth is a constitutional cause of irregularity. When there is a difference between these diameters the line formed by the teeth must either fall outside or within the arch of the maxilla and irregularities of arrangements result. The primary division of irregularities is the V-shaped and saddle-shaped arches. We have the V-shaped variety (Fig.90, one of the typical forms), where the apex of a triangle is formed by the incisors, the base of the triangle being a line connecting the first two molars. If, because of premature or tardy extraction, the first molars move forward, or by coincidence of the arch of the maxilla and the arch of the crown of the teeth in trying to accommodate itself to the lesser arch of the maxilla, the arch becomes a broken line, forming an angle at the incisors. This angle results from two causes: the thinness of the process at this point and the diminution of resistance which must follow.
When the permanent bicuspids erupt under a favourable condition, so that their greatest diameter is in a line with the greater diameter of both cuspids and first molar, they will be held firmly in place, since the greatest pressure is on this very line. On the other hand, when the bicuspids are erupted after their proper time, while the cuspids progress duly, and meeting no resistance fall into their proper places, but the bicuspids adapt themselves as best they can to the space left for them, and if the arch of the maxilla does not coincide with that of the crowns, they must fall within or without the arch.Now, if the first molar have moved forward, diminishing the space, the bicuspid must erupt either within or without the arch.
FIG. 91.
To understand why they are generally found within the arch, the shape of the molar and cuspids must be kept in mind. A transverse section of their crowns shows their proximal walls not to be parallel, but wedge-shaped, their diameter being greater on the buccal than on the palatal side. When thecrowned bicuspid falls within the greatest diameter of these teeth, finding more room within the arch, they naturally slip in the direction of least resistance,i.e., toward the palate. A local cause for the same condition is found in the fact that the crown of the bicuspids, before their eruption, was held between the roots of the temporary molars, and, as these form an arch of a smaller circle than that of the permanent teeth, the bicuspids will be found generally inside the arch. From both causes occurs an inward curvature, which is termed the saddle-shaped arch (Fig.91). It should be noted here that, since the V-shaped irregularity is found anterior to the cuspid, the upper incisors are always projecting beyond the lower; the saddle-shaped irregularity is invariably posterior to the cuspid from an inward curve. The incisors never project. Both forms contract the arch; the V-shaped anteriorly, the saddle-shaped posteriorly. In both forms the forward movement of the first molar is the local cause.
Deformities of the dental arch are due, first, to arrest of development of the jaws, and, second, in the nature of the deformity, to the order of eruption of teeth, which rarely erupt twice alike. From an evolution standpoint these deformities are atavistic. The V-shaped reverts to the reptilian type; the saddle-shaped to the lower mammals. In the gorilla, the nearest to man in dentition, there is a very distinct approach to the saddle shape. In the chimpanzee it remains. The orang-outang exhibits less of this tendency. The arch of some of the cebidæ very nearly approaches man. It all depends upon the extent of prognathism. When that is reduced the arch appears and rectangular arrangements of theteeth are lost. Most carnivors exhibit a distinct approach to the saddle shape. Some felines have a shortening of the jaw, partly obliterating the tendency, but in most canidæ it is quite marked.
These are facts which cannot be overlooked, since, from the very nature of development and eruption of the teeth, they cannot take any other form. The arrangement of the crowns of the cuspid (canine) in the jaw before eruption is such that, no matter what the local condition of the jaws or teeth may be the V-shaped or saddle-shaped dental arch must be produced.
FIG. 92.
In no symptoms is degeneracy so evident as in the stigmata resultant on hypertrophy of the alveolar process. This occurs at all ages, but more particularly at the period of development of the permanent set of teeth. The entire alveolar process may become involved (Fig.92), or only a portion (Fig.93).
Hypertrophy of the alveolar process is the result of irritation incident upon eruption and the shedding of the temporary teeth, and eruption of the permanent teeth.
FIG. 93.
Laryngologists, rhinologists, and neurologists claim that certain vaults are deformities; in reality the alveolar process is hypertrophied. The jaws, as a whole, owing to an unstable and ill-balanced nervous system, are liable to become excessively developed, as well as arrested in development. Excessive development of the superior maxilla is evinced by a fulness of the upper lip. In these cases the upper maxilla is too large for the lower, and stands out beyond it. The lower may be quite normal. When there is simply a want of proportion between the two jaws, it is due to the diminutive or excessivesize of one while the other is normal. The criterion in these cases must be the facial angle. The upper jaw is usually in harmony with the skeleton, while the lower jaw depends for its size largely upon function, its size being the result of accident rather than the result of general proportions.
FIG. 94.
When the upper jaw is normal, or smaller than the lower, the extent of the posterior portion is determined by the occlusion of the first permanent molar, which keeps the alveolar processes in permanent relation to each other at this point and allows freedom of development in front. If the occlusion be not normal, the upper jaw and alveolar process will develop laterally as well as anteriorly. The teeth of the anterior columns may either stand vertically, or they may be turned in toward the lower incisors. The latter defect is produced by the action of the lips. When the cuspids are in their normal position the upper incisors form a larger arch than the lower, and this permits of their being turned inward; but when the cuspids have moved so farforward that they are not normally interlocked with the lower teeth, the incisors are too crowded to permit this. While the jaws are growing smaller the teeth tend to cause reversion to the original form. Arrest of development of the superior maxilla is always associated with marked depression at the alæ of the nose, producing the appearance of having been hollowed out from a point at the floor of the orbit to the grinding surface of the lower teeth (Fig.94).
FIG. 95.
Arrest of the lower jaw (Fig.95) is common among degenerates. This consists of a shortening of the body of the jaw. Sometimes it is arrested to such an extent that there is apparently no chin. About 50 per cent. of criminals of Elmira, New York, have this deformity. The following table shows the number of deformities of the jaws and teeth which I have found among some of the degenerate classes.
Degeneracy of the Body
Asdegeneracy checks the natural course of embryonic development it necessarily finds expression in the body as well as in the skull. One most striking condition is that by which development of the bones enclosing the spinal cord is checked. The spinal cord is at first essentially a notochord as in the lowest types of vertebrates. The structures surrounding the cord are not divided into vertebræ. This condition is permanent in the lancelet. Around the notochord is later formed a species of membrane which protects it, called the perichord. This condition is the second stage of development of the cord and is the permanent condition in the lampreys. Later still the cartilaginous vertebræ develop, and then these ossify at the point in the perichord which is to form a vertebra, bows of dense tissueformwhich unite behind. In front similar bows form to constitute the bodies of the vertebræ. These bows remain ununited in some of the lower fish and at certain stages in the human embryo. As degeneracy checks the union of the bows of the vertebræ, imperfection, and even absence, of the union occur, which is called spina-bifida (Fig.96). This conditionwhen complete is rarely compatible with life. In a partial state it is often found among degenerates.[220]The seat of the trouble is frequently covered by an excessive development of hair (hypertrichosis), especially in the small of the back; this, which occurs very frequently in degenerates, resembles the tail which the ancients represented as that of the fauns.[221]
FIG. 96.
As the vertebræ unite irregularly, deviations or bends of the spine occur very frequently among degenerates. These may be of any of the types known to surgeons. In man the spinal column terminates in two bones. One of those (composed of five vertebræ) begins at eighteen years to unite slowly into a single bone called the sacrum. The bones of the sacral vertebræ form processes similar to those which areformed from the vertebræ of the chest region. These serve to cover the nerves of the sacral region. The bone immediately below the sacrum, called the coccyx, is essentially the representative of the tail in man. At a certain stage of human development, as in the tadpole, the tail disappears, the nine vertebræ forming the coccyx unite together and become a very diminutive bone whichlosesnearly all vertebral characteristics. Sometimes this bone retains its embryonic peculiarities to such an extent that it simulates in some degenerates a rudimentary tail. Of this many instances are on record. A greater degree of this condition has been found to occur, with comparative frequency, amongst the lowest negro races. In this respect these are below the anthropoid apes, where the tail, considered from the tail standpoint, has degenerated as in man for the benefit of the organism as a whole.
FIG. 97.
The ribs and breastbone develop from the processes of the vertebræ. It is probable that every vertebra originally had ribs. Traces of these exist in most vertebræ in the human embryo. In man, as a rule, there are but twelve vertebræ which develop true ribs. In degenerates, as in the gibbon, a thirteenth pair sometimes appears. Normally, the two lowest ribs are, however, very imperfectly developed as compared with the other ten, and one is sometimes absent. The rib develops from the ends of the vertebral bows, which, coming in contact with the muscle plates of their own segment of the body, are by the resulting bulging forced to expand, and later come together through the formation of the breastbone. Checking of these conditions produces various deformities of the chest which have beendivided into “funnel-shaped” and “dropper” deformities.[222]Frequently the entire chest wall is arrested early in life (Fig.97). The relation between the muscle plates and the course of development of the chest is illustrated by the fact that an arrest of development of important muscles often coexists with deformities of the chest. The human limbs are developments from the fin-folds as found in fishes and the human embryo. In one of these the fins are divided into four segments. The upper segment contains one long bone, the humerus (or arm bone), or the femur (or thigh bone). The second segment contains two long bones, the radius and ulna (or arm bones), or the tibia and fibula (or leg bones). The third segment consists of nine small bones, the carpals of the wrist or the tarsals of the ankle. The fourth segment consists of five separate digits. These limbs pass through three stages in embryonic development as to their position, which may be designated as amphibian, reptilian, and mammalian. Many of these bones fuse together (carpals and tarsals). The digits have long before the late fish stage been formed of more than one bone. At times this condition persists even after the completion of human embryonic development. Limb anomalies resulting from checks of development causing either excess or arrest of development are far from uncommon among degenerates, but are not so common as anomalies of form and proportion. Among such anomalies may be mentioned joined limbs (symelia), or the more or less complete absence of limbs (ectromelia), or the absence of a peripheric segment (hemimelia), or the complete or partial absence of a central segment(phocomelia). Among the other important degeneracies of the limbs are supernumerary digits. These Annadale[223]classifies as: First, a deficient digit loosely attached to the hand or foot or to another digit. Second, a more or less developed digit free at its extremity and articulating with other bones. Thirdly, a fully developed separate digit. Fourth, a digit united along its whole length with another digit. The first three types have been called polydactylia. The last has been called syndactylia. There is finally a condition in which union between the digits results in the disappearance of some of the fingers and toes (Fig.98). This condition is called ectrodactylia. Supernumerary digits to the extent of six fingers and six toes are exceedingly common in the families of degenerates. The influence of heredity in this particular has been well demonstrated. The Kelleia family of Malta was one of the earliest reported. The condition may last for five generations,[224]but often disappears on marriage with normal persons outside the community or family. A family of the Arabian Hyabites, named Boldi, confined marriages to their own tribe. They all have twenty-four digits. Children born with a normal number are killed as being the offspring of adultery. The inhabitants of Cycaux, France, till the end of the eighteenth century, had nearly all supernumerary digits either on the hands or feet. Isolated in a mountainous region, they for years intermarried. On communication being opened, they emigrated or married strangers, and sexdigitism vanished. Maupertius reports the case of a German family whose members had twenty-four digits for many generations.[225]One of them refused to acknowledge a normal child. In one instance in the United States supernumerary digits lasted through five generations. A case reported[226]some years ago was the following: The first instance of the appearance of the deformity was in a man, born of a degenerate family in 1752, who had six toes on one foot. His son was born with six toes on one foot, but the daughter was normal. This daughter had five children; among them were a son and daughter, each of whom had six fingers on one hand. The granddaughter had eight children, including one son with six toes on one foot. Another son had two daughters, each having six fingers on each hand, and one daughter having twenty-four digits. This last girl had three children; the son was doubly deformed like his mother, while a second son had six fingers on each hand, the toes being normal. One of the two daughters of the fourth generation (with only the hands affected) had eight children, several of whom were normally developed, but the rest were deformed as follows: One daughter had an osseous thickening at the end of the digits, one son had twenty-four digits, another had twelve fingers, the toes being normal in number.
FIG. 98.
FIG. 99.
I have elsewhere cited an instance from Kiernan in which unilateral sexdigitism was found in four generations of Norwegian degenerates.
Not unfrequently polydactylia is associated with the absence or union or decrease in size of bones of the limbs. It happens that the upper or lowerextremities may be increased or diminished disproportionately through the body. This disproportion in size of the fingers and toes is exceedingly frequent. Big digits (macrodactylia, Fig.99) are comparatively rare, and may only involve a supernumerary bone in the thumb. Short digits (microdactylia) are much more frequent. This state may be constituted by the absence of one bone or the union of two bones, or the shortening of metacarpal or metatarsal bones, or the shortness of several phalangeal bones. There may be increased disproportion between the different fingers. The method of determining this is by comparison with the middle finger. This disproportion may vary greatly. Féré is of opinion that shortening of all the fingers constitutes a grave mark of degeneracy. Relative shortness is exceedingly common.
Under the conditions of development of the limbs from the fin-fold, it follows that these may be checked completely so that the condition approximates the earlier development from the fish. On the other hand the large bones of the arm and thigh may be checked while the digits and the two lower bones (radius and ulna, tibia and fibula) go on to full development as do the digits. Sometimes the arms develop completely while the lower extremity remains in the fin-fold state. On the other hand the arms may be checked and remain in the fin-fold state while the legs go on to full development. Sometimes the bones of the arm and forearm are checked while the digits go on to full development. The lower extremities are sometimes fused together. This condition, from its resemblance to the like state in the seal, is called phocomelia, or seal limbs. They arealso called sirens, on account of the resemblance to the sirens of mythology.[227]
FIG. 100.
Other expressions of degeneracy, albeit sometimes secondary, are club-foot and club-hands (Fig.100). In many instances these are retentions of positions assumed by the limbs of the fœtus in the course of evolution, and are therefore, in the adult, expressions of degeneracy. Club-foot was an expression of degeneracy which appeared in Byron, the poet, as a consequence of the degeneracy present in both the Byrons and the Gordons, as Kiernan has shown.[228]Commenting on this condition as found in Byron, F. S. Coolidge, of Chicago, remarks: “Byron undoubtedly suffered from double congenital club-foot, the deformity being worse on the right.” While in Coolidge’s opinion congenital club-foot unquestionably arises from different causes, it is, however, so frequently an accompaniment of severe forms of mal-development and of congenital brain defects, that there can be no doubt but that imperfect constitutional development is one of its causes. That the deformity with the many limitations which it involves may tend to create morbidness is very likely to be an additional symptom of the degeneracy which, in certain cases, is the underlying cause for the deformity. Dareste, who has studied the club-foot and the club-hand from the standpoint of experimental teratology, finds that in no small number of cases club-foot and club-hand result from checked development. Absence of the kneecap or patella may, as H. N. Moyer has shown, be an expression of degeneracy.[229]
The conditions resultant on checked development may appear in any of the bony or muscular structures. At times muscles checked in development pass on to conditions present in the lower apes.[230]Sometimes the checked development of bones results in artery courses which are present in some of the lower animals. Just above the bend of the elbow in the embryo is an opening through which an artery passes in many quadrupeds. In adult man, as a rule, this has disappeared, but not rarely in degenerates the opening persists with the artery through it.
Hernias, of all varieties, are noticeably hereditary,[231]but what is hereditary is not the rupture, but the laxity of the orifice of the cavity of the abdomen. As descent of the testicles from the abdomen (where they are embryonically in man and normally in many animals) is often delayed and even does not occur in degenerates, hernia of the groin variety is particularly apt to occur in them. These hernias are often found united with defects of the testicles as well as deficiencies of the chest. Deformities of the nose are also especially apt to coexist with these.
Degenerate women frequently have supernumerary milk glands arranged on the abdomen as in some lemurs, while males may have supernumerary breasts of either male or female type. These breasts may be represented by nipples alone. In either sex arrested development of the face, middle ear, and palate often coexists with these supernumerary breasts.
The degeneracies of the body combine so frequently with those of the skull and the brain as to indicate a common origin. Polydactylia is found with almost all the degeneracies of the body. It occurs with all the degeneracies of the eye, from those which are purely atavistic like coloboma to those like retinitis pigmentosa and amauroses, which are atavistic in origin. Hare-lip, cleft palate, and deformities of the jaws and teeth are often found associated with all the bodily degeneracies and the nutritive, intellectual, and moral degeneracies as well. Phocomelia with brain deformity has been found associated with them. Anomalies of the genital organs are also quite frequently associated with these and with finger anomalies. In the subjects of juvenile obesity are frequently associated unstable mentality and will-power, and delayed or precocioussexual maturity. My own observations have shown this condition to be frequently associated with the jaw and teeth degeneracies.
FIG. 101.
Aside from their general significance as stigmata of degeneracy, anomalies of the external ear have been found frequently associated with mal-development of lungs, kidneys, liver, and intestines. Hidden spina-bifida is often associated with the same anomalies, and not rarely with irregular development of the genital organs of both sexes. Albinism or deficient pigment in the skin and hair is not only often associated with grave degeneracies, intellectual and moral, but appears combined with mal-developmentof the spleen, liver, and kidneys. The opposite state (melanoderma, or black skin) is often associated with similar deformities, especially with early precocity in development. It has also been found in connection with hairlessness and irregularities in development of the teeth and jaws.
The deformities of the chest and their resulting interferences with respiration are not only associated with conditions like narrowing of the pulmonary artery, of the aorta, and with cardiac deformities, but also lead to diminution of the respiratory power and, in consequence, to conditions predisposing to pneumonia and consumption. They are also, as my own observation has shown, associated with deformities of the face, of the nose, of the mouth cavity, of the palate, and of the jaws. These conditions result in mouth breathing and in other conditions which predispose to the attacks of microbes. The deformities of the arterial system coexisting with checked development of the chest are apt to extend to the blood vessels of the kidneys, and therefore to retain these in the embryonic condition, thus predisposing them to disease. To a somewhat lesser degree this arterial condition coexisting with checked development of the chest or with the other arrested conditions of development associated with it, may extend to the liver in such a degree as to prevent it destroying the toxins of typhoid fever and allied diseases, thereby increasing the dangers from these disorders. The same influence may be exerted on the spleen and suprarenal capsules, thus interfering with the physiologic guards these organs furnish against disease and its results. Not infrequently do these last conditions tend to give an epilepticcharacter to degeneracies which would otherwise be destitute of it. With the interference with the proper blood supply, due to checked conditions of the organs named, may occur gout, diabetes, and many forms of rheumatism with their secondary consequences.
The imperfect and irregular action of the lungs associated with the arrests in development of the face, nose, palate, jaws, and chest may produce an irregular blood supply to the brain, which will exaggerate the mental instability of the degenerate.
Among the conditions which are expressions of degeneracy of the body, combined with degeneracy of the head and face, are three conditions known as infantilism, masculinism, and feminism. Practically all three are arrests of development of the promise of the child type. Owing to the struggle for existence which occurs at puberty between the old type of the chondrocranium and its new type as supplemented by the dermal bones, the nervous system takes a distorted ply which arrests both the bodily, nervous, and mental development at certain points. In infantilism the arrest is of the future promise of the child, so that the body and face remain at the childish point, or the body and nervous system are checked, or finally the nervous system or certain organs alone are checked while the body goes on to full development. Not infrequently the face is arrested at any period from birth to puberty (Fig.101). Hence the reason many persons retain their youthful appearance throughout life. These people are often vain and egotistic. The mental stamina is weak, and they are frequently unreliable, while the females are often prostitutes or prurient prudes, hysteric reformers or gossip mongers.