NOTES ON THE ZYGNEMALES.[A]Edgar Nelson Transeau.
Edgar Nelson Transeau.
The following notes principally concerning North American Zygnemales are based on a study of the specimens accumulated in the course of eight years collecting in central Illinois; a collection made by Mr. Charles Bullard, of Cambridge, Mass., in Massachusetts and New Hampshire; the specimens distributed in the Phycotheca Boreali-Americana by Collins, Holden and Setchell; the specimens distributed in American Algae, by Miss Josephine E. Tilden; the specimens in the U. S. National Herbarium; and small collections sent me by Professor Farlow, Miss Tilden, Professor A. B. Klugh, Professor D. S. Johnson and Miss Grace Stone. They have been compared with the species distributed by Wittrock and Nordstedt in their “Algae Aquae dulcis exsiccatae,” and other valuable European and South American specimens sent me by Professors O. Borge and O. Nordstedt.
In determining almost any species of the Zygnemales it is absolutely essential that the specimens show both the vegetative cells and the mature spores. With the exception of a few species of Mougeotia the spores are colored either yellow, brown, or blue when they are mature. The characteristic markings of the median spore wall do not develop usually until this color appears. Consequently it is useless to attach names to vegetative specimens based on dimensions and number of chromatophores. Keys based on such characters are not only useless, but misleading.
Judging from my experience in Illinois it is highly probable that the list of North American forms will be considerably augmented, when intensive studies have been made at localities in the Southern United States. The most satisfactory method of collecting these forms is to take samples from the various ponds and streams at regular intervals of ten days, or two weeks, throughout the growing season. Many of the species show local variations and considerable experience is needed before many of the forms can be satisfactorily classified. The writer has in course of preparation an illustrated key to the group, in which figures for all of the species will be published.
This genus is in many respects the most generalized of all theZygnemales. It is distinguished by three important characteristics: (1) the entire contents of the gametangia enter into the making of the zygospore; (2) the zygospore is formed in the conjugating tube and is not cut off from the other parts of the gametangia by partition walls; (3) as the gametes move toward the tube during conjugation, their place is taken by a secretion of cellulose, which renders the gametangia solid and highly refractive. This secretion also occurs when a vegetative cell forms an aplanospore.
This species has been recorded for America. It is not uncommon in Massachusetts and has also been found in Minnesota and Florida. In P. B.-A. No. 808 from Boswell, California is a somewhat smaller variety with blue spores associated withZygnema peliosporumWittr. The spores are common in the material and the vegetative cells and filaments occasional. Following is a diagnosis for this variety:
Var.formosanov. var. Cellulis vegetativis 7.5-9µ latis; zygosporis 24-30µ × 30-42µ, caeruleis; ceterum ut in typo.
Vegetative cells 7.5-9µ in diameter, zygospores 24-30µ × 30-42µ steel blue, otherwise like the type.
Cellulis vegetativis 9-12µ × 27-120µ, ad dissepimenta constrictis; chromatophoris cum pyrenoidibus 2; cellulis fructiferis, 10-14µ × 75-180µ; zygosporis ovoideis vel quadrato-ovoideis, 20-40µ × 30-40µ, angulis rotundatis, productis, vel retusis; parthenosporis 15-20µ × 20-30µ, oblique ellipticis, cum polis retusis; mesosporio subtiliter et irregulariter verrucoso, maturitate luteo-brunneo.
Vegetative cells 9-12µ × 27-120µ constricted at the end walls, chromatophore with two pyrenoids; fertile cells 10-14µ × 75-180µ; zygospores ovoid or quadrately ovoid, 20-40µ × 30-40µ, with angles rounded, produced, or retuse; parthenospores 15-20µ-× 20-30µ unilaterally ellipsoid with retuse ends; median spore wall minutely and irregularly verrucose, yellow-brown at maturity.
This species was collected by Professor A. B. Klugh, Kingston, Ontario. It is the material upon which the Ontario record forMougeotia calcarea(Cleve) Wittr. is based. Of special interest is the chromatophore with two pyrenoids, which although an axile plate is distinctly two-lobed and forms an easy transition to the next species, in which the chromatophore resemblesZygnema. Type in herb. E. N. T. Collection No. 2950.
Cellulis vegetativis 16-20µ × 25-50µ cylindraceis; chromatophoris asteroidiis duobus, singulis cum pyrenoidibus (ut in Zygnemate); zygosporis vel ovoideis, vel irregularibus, 24-30µ × 30-48µ cum angulis vel rotundatis, vel retusis, vel productis; aplanosporis uno latere ovoideis, 17-25µ × 20-40µ; parthenosporis 15-20µ × 20-30µ; membrana media sporarum scrobiculata, luteo-brunnea; akinetis ad dissepimenta constrictis, membrana subcrassa et glabra, 18-20µ × 20-36µ.
Vegetative cells 16-20µ × 25-50µ cylindrical; chromatophores two, stellate, each with a pyrenoid (as in Zygnema); zygospores ovoid, quadrate-ovoid, or irregular, 24-30µ × 30-48µ, with rounded, retuse, or produced angles; aplanospores unilaterally ovoid, 17-25µ × 20-40µ; parthenospores 15-20µ × 20-30µ; median spore walls scrobiculate, yellow-brown; akinetes with smooth heavy walls, 18-20µ × 20-30µ.
Type in herb, E. N. T. Collections No. 1177, 1939, 1949, 2686 and 2918. I have specimens from several localities in central Illinois; Williamsport, Pa.; Minnesota; Mackinaw, Mich. and Kingston, Ontario.
This form is of great interest because of its resemblance, in the vegetative condition, toZygnema decussatum(Vauch.) Transeau. Also because it shows not only the zygospores, but aplanospores and parthenospores. In all cases the secretion of cellulose accompanies the process of spore formation. The unilaterally placed aplanospores are strikingly different from those formed by the Zygnemas. In some of the Illinois ponds it regularly produces only zygospores, in other ponds from which I have collections covering a period of several years it fruited only asexually, producing aplanospores and akinetes. But several of the collections show all the forms of reproduction in different cells of the same filament.
The characteristics of this species suggest that the peculiarZygnema reticulatum, which was described by Hallas in 1895[B], is in reality aDebarya. The fact that the reproductive cells become filled with cellulose, that the aplanospores are very irregular in form and that the vegetative cells contain as high as seven chromatophores, are all in harmony with this idea. On this basis it is also easy to understand the most notable peculiarity of the species—that spores derived from cells with several chromatophores produce two or three sporelings.
With the addition of the two new American species and this Danish speciesDebarya reticulata(Hallas) nov. comb. the description of the genus needs to be modified as follows:
Vegetative cells cylindrical or constricted at the ends, varying from 1-16 diameters in length; chromatophore varying from an axile plate with two or more pyrenoids to stellate chromatophores, each with a central pyrenoid. Reproduction by zygospores formed of the complete contents of the gametangia; not cut off from the gametangia by partition walls; but in the process of conjugation, as the gametes pass into the conjugating tube, their place is taken by a secretion of cellulose. Aplanospores occupying only part of the sporogenous cell, the remainder being filled with cellulose. All spores variable in form. Parthenospores and akinetes occur not infrequently in some of the species. The walls of the aplanospores and parthenospores resemble the zygospores of the same species in their markings.
There are now eleven described species belonging to this genus.D. immersaW. West andD. africanaG. S. West bear a close resemblance toMongeotia sphaerocarpaWolle.D. HardyiG. S. West has much the same appearance asMongeotia viridis(Kutz) Wittrock.D. desmidiodesW. & G. S. West,D. calospora(Palla) W. & G. S. West,D. reticulata,D. americana, andD. decussatahave characters in common with the Zygnemas.D. glyptospermahas the vegetative characters common to several of the species, but its spores are quite unique among theZygnemales.
This is probably common in the eastern half of the United States at least. In Illinois along with the type occurs the varietyconspicuum(Hass.) Kirchner, and a variety with large spores. This latter variety in fact is more common than the type.
var.crassumnov. var. Cellulis vegetativis 30-40µ × 20-80µ; zygosporis 40-55µ × 50-60µ, ceterum ut in typo.
Vegetative cells 30-40µ × 20-80µ; zygospores 40-55µ × 50-60µ, otherwise like the type. Type in herb. E. N. T. Collections No. 2350, 2392, 2660, 2685.
Professor G. S. West has studied the reproduction of this species and finds that it is a true Zygnema and that the description and figure by De Bary, which shows the cutting off of two special gametangia before the union of the gametes is at fault, consequently there is no longer any need of maintaining the genusZygogoniumKützing.
Specimens of this species have been distributed under the name ofZ. chalybeospernumHansgirg, in P. B.-A. No. 808 from Boswell, Calif. (N. L. Gardner); Amer. Alg. No. 156 from Ft. Collins, Colo. (J. H. Cowan); and Amer. Alg. No. 392 from Vancouver, B. C. (J. E. Tilden).Z. chalybeospermumhas the median wall smooth, but the spores of all of the above specimens have distinctly scrobiculate median walls. In size the specimens show a somewhat greater variation in dimensions than has been recorded for European localities.
Specimens of this species have been found at Fath Pond, north of Coffeen, Ill., in which both zygospores and aplanospores occurred in abundance. The aplanospores fill or slightly enlarge the vegetative cells as inZ. CollinsianumTranseau,[C]but the ends of the spores are usually more nearly truncate, 34-50µ × 30-80µ. At Casey, Ill., a variety with the same dimensions but steel blue spores occurs in the old Ice Plant Pond.
var.caeruleumnov. var. Cellulis vegetativis et sporis ut in typo, sed membrana media sporarum caerulea.
Vegetative cells and spores as in the type, except that the median spore wall is steel blue. Type in Collection E. N. T. No. 495.
The specimen distributed under the nameZ. insigne(Hass.) Kütz. in the P. B.-A. No. 457, from Chestnut Hill, Mass. (G. F. Moore), belongs to this species as shown by the scattered mature spores. This species is common everywhere in central Illinois. In the U. S. Natl. Herb, is a specimen from Baltimore Co., Md., (J. D. Smith). In Amer. Alg. No. 157, a specimen from St. Paul, Minn., (J. E. Tilden) shows both zygospores and aplanospores. The aplanospores are cylindric ovoid in form, occupying the entire cell 30-33µ × 40-88µ, median wall scrobiculate.
Cellulis vegetativis 28-33µ × 28-66µ; zygosporis incognitis; aplanosporis cylindricis vel tumido-cylindricis, 30-33µ × 24-58µ, sporangia complentibus; membrana media brunnea scrobiculata.
Vegetative cells 28-33µ × 28-66µ; zygospores unknown; aplanospores cylindric or tumid-cylindric, 30-33µ × 24-58µ, filling the sporangia, median wall brown, scrobiculate. Type in Herb. E. N. T. No. 1164, 1177.
This species is not uncommon in ponds, and pools throughout central Illinois. It was at first classified as aplanosporic material ofZ. stellinum(Müller) Agardh. On going over the specimens in all my collections, however, it was found that in no case were the filaments containing the aplanospores connected with the filaments containing zygospores. This must be the final test of the identity of the species, as it occurs in some collections alone, sometimes associated only with fruitingZygnema pectinatum, and sometimes withZ. stellinum.
In a collection of algae made at the Minnesota Seaside Station, Vancouver Island, B. C., in 1901, by Professor Tilden, is a form which perhaps belongs here. The vegetative cells are from 22-28µ in diameter, and 32-52µ in length, while the European specimens are described as16-20µ in diameter and 2-6 diameters long. The Vancouver specimens are producing both aplanospores (globose, 24-26µ in diam.), and zygospores (ovoid 24-28µ × 36-44µ) by the union of gametes through the partition wall separating the two gametangia. The specimens show some evidences of being in an abnormal condition.
The specimen in P. B.-A. No. 510 from Knightsville, R. I., distributed under the name ofS. longata(Vauch) Kütz. with cell diameter 27-30µ, and ellipsoid spores 30-33µ in diameter, fertile cells enlarged, evidently belongs to this species. The spores ofS. longataare distinctly ovoid with rounded ends. In the Illinois specimens the spores ofS. Juergensiifrequently occur with diameters up to 33µ.
The varietiesscrobiculataStockman andminorTeodoresco have not been reported from America. They both occur rarely in Illinois. The latter I have also seen in material collected by Mr. Charles Bullard, at Lynnfield, Mass. The former is characterized by its scrobiculate spores, the latter by its smaller dimensions throughout. In my herbariumS. varians scrobiculatais represented in Collections No. 1799, and 1881; andS. varians minorin Collection No. 2951.
Cellulis vegetativis 30-35µ × 50-200µ, dissepimentis planis, chromatophoris singulis anfractibus arctis 1.5-5; cellulis fractiferis altero latere inflatis, altero latere (in quo conjugatio sequitur) rectis; zygosporis ellipticis, 33-40µ × 54-70µ, membrana media flava, glabra.
Vegetative cells 30-35µ × 50-200µ, end walls plane, 1 chromatophore making 1.5-5 turns; fertile cells inflated on the outer side, straight on the conjugating side; zygospores ellipsoid 33-40µ × 54-70µ, median wall yellow, smooth. Type in herb. E. N. T. Coll. No. 1883, 1890. Charleston, Illinois.
This species bears some resemblance to a form ofS. variansfigured by Professor Borge.[D]It differs from his figure in that the conjugating side of the fertile cells is not at all swollen, and the dimensions are somewhat larger. If this form had been found but once it would have been passed over as a variation intermediate betweenS. JuergensiiandS. varians. But it has been found several successive years in a small stream south, and at a small pond west of Charleston, Illinois.
So far as I am aware no specimens of this species have been found in America. The Illinois record in my list[E]is an error. The P. B.-A. specimen labelledS. lutetianaisS. fallax(Hansg.) Wille, as shown by its often replicate cell walls, verrucose spores and the number of chromotophores.
Specimens of this variety have been distributed in the P. B.-A. No. 96, under the name ofS. dubiaKütz. var.longiarticulataKütz. from Oak Bay, Victoria, British Columbia (N. L. Gardner). The spores are for the most part not mature but they show the characteristic scrobiculate markings of the median wall.
This species is not uncommon in central Illinois. The specimen labelledS. communisin P. B.-A. No. 1416, from Winchester, Mass., has a cell diameter over 30µ, and the spores are ellipsoid instead of ovoid. The median spore wall in the mature spores is punctate. Here also belongs the P. B.-A. specimen No. 365, Falmouth, Mass. Both the vegetative cells and the spores are considerably below the lower dimensions forS. porticalis. The P. B.-A. specimen No. 1668,S. porticalisvar.tenuispiraCollins establishes this name as a synonym ofS. Lagerheimii. Professor Farlow has recently sent me a specimen of this species from Chocorua, N. H.
This species has recently been found in a pond south of Coffeen, Ill. The spores show the characteristic markings and the dimensions are near those of the original collection. The spores are slightly more rhomboidal than in the type material, which I have seen. In herb. E. N. T. Collection No. 2912, 2850.
This species previously known only from the tropics has been found in the collection of Mr. Charles Bullard, from Wellfleet, Mass. In herb. E. N. T. Collection No. 2954.
This species was described by Collins as a variety ofS. decimina(Müller) Kütz, which it somewhat resembles in the form of the vegetative cells. The spores, however, are distinctly ellipsoid, while those ofS. deciminaare ovoid. The dimensions are much smaller than those ofS. decimina. It seems better therefore to recognize this as a distinct species. It has been collected in Massachusetts, Connecticut and Bermuda.
Described originally from Illinois, I have seen specimens during the past year from Maine, Massachusetts and Minnesota. Professor G. S. West[F]described about the same time a species from Columbia, South America, which appears to be a form of this same species. The vegetative cells are considerably larger, the chromatophores are six (or five) in number, and the spores are at the upper limit of size of the North American form. As our specimens all show, a wider range of dimensions and number of chromatophores, the South American form is best classified as a variety under the nameS. ellipsosporavar.splendida(G. S. West) nov. comb.
Cellulis vegetativis 60-68µ × 80-150µ, dissepimentis planis; chromatophoris 3, anfractibus arctis .5-1; cellulis fructiferis cylindricis; zygosporis ellipticis 42-60µ × 80-120µ; membrana media sporarum scrobiculis irregularis ornata, luteo-brunnea.
Vegetative cells 60-68µ × 80-150µ, end walls plane; 3 chromatophores making .5-1 turn in the cell; fertile cells cylindrical; zygospores ellipsoid, 42-60µ × 80-120µ, median wall irregularly pitted, yellow-brown. Type in herb. E. N. T. Coll. No. 2666. Coffeen, Illinois.
This species is very distinct in the form of its spores and their position in the fertile cells. Lateral conjugation only has been observed. It is possible that the number of chromatophores is more variable, but in all the vegetative cells in which they could be counted there were three.
Owing to the indefinite and imperfect description ofS. lineataSuring., the varietyBraziliensisNordstedt, of which we have a perfect description and specimens (W. & N. Alg. aq. dulc. exsicc. No. 360), should be given specific rank. Its connection withS. lineatais very problematical.
In all the published descriptions of this species the spores are described as smooth, and the number of chromatophores is given as four. I have seen many specimens from Illinois, and collections from the upper peninsula of Michigan (T. L. Hankinson), Minnesota (J. E. Tilden), Hawaii (J. E. Tilden), Massachusetts (P. B.-A. No. 1217), Pennsylvania (E. N. T.) and Guatemala (W. A. Kellerman). In all cases the mature spores are brown and scrobiculate, and the number of chromatophores is three or four.
Cellulis vegetativis 50-60µ × 200-350µ, dissepimentis planis; chromatophoris 3-5, anfractibus arctis 2.5-4.5; cellulis fructiferis non inflatis; zygosporis ovoideis 50-65µ × 80-120µ: membrana media sporarum reticulata et dense punctata, flava.
Vegetative cells 50-60µ × 200-350µ, end walls plane; 3-5 chromatophores making 2.5-4.5 turns; fertile cells not inflated; zygospores ovoid 50-65µ × 80-120µ: median wall reticulate and densely punctate, yellow in color.
This species was first found in the collections of Mr. Bullard from Beaver Dam, Brook Pond, Natick; the pond west of Winter Pond, Winchester; and the Middlesex Fells, Mass. Recently the same form was found in a large prairie pond south of Coffeen, Illinois. Its position in the genus is nearS. malmeanaHirn. In herb. E. N. T. Collections No. 2952, 2953 and 2900.
I first came across this species in Mr. Bullard’s collection from the pond west of Winter Pond, Winchester, Mass. On going over Wood’s description, its identity withS. dilutais unmistakable. The position, color and form of the spore, and the shape of the fertile cells is perfectly represented in Wood’s figure. The dimensions also correspond. Wolle is responsible for confusing this species withS. nitida(Dillw.) Link, but a glance at Wood’s figure is sufficient to show that it is very different from that species. The P. B. A. specimen No. 513 (labelledS. nitida) from Bridgeport, Conn., belongs here. Miss Grace Stone also sent me a collection of this species from near New York City. In the U. S. National Herbarium is another specimen from Bois Sabbi, Louisiana, April 7th, 1891, (A. B. Langlois). Recently the species has been collected at Donnelson, Illinois, by Mr. Frank Harris.
The vegetative cells are usually shorter than inS. nitida, the spores are ovoid, not ellipsoid, and the spore wall is verrucose, or reticulate-verrucose, chestnut brown in color. In herb. E. N. T. Coll. No. 2900.
Var.formosanov. var. Varietas gracilis, cellulis vegetativis 80-95µ × 80-270µ; zygosporis 88-100µ × 120-150µ × 70-90µ; ceterum ut in typo.
A small variety, vegetative cells 80-95µ × 80-270µ: zygospores 88-100µ × 120-150µ × 70-90µ; otherwise similar to the type. Type in herb. E. N. T. Coll. No. 1939. This variety occurs in a pond east of Ashmore, Ill.
This species which was described from Illinois has been found with nearly the same dimensions in the collections from Middlesex Fells, and South Peabody Station, Mass., sent me by Mr. Chas. Bullard.
Cellulis vegetativis 30-36µ × 120-300µ, dissepimentis planis, chromatophoris singulis anfractibus arctis 3-7; cellulis fructiferis modo binis vel quaternis inter cellulas vegetativas distributis, modo continuis, altero latere (in quo conjugatio sequitur) inflatis, altero rectis; tubo conjugationis plerumque ex cellula mascula emisso; zygosporis ellipticis 37-42µ × 57-100µ membrana media micropunctata et lutea.
Vegetative cells 30-36µ × 120-300µ, end walls plane; 1 chromatophore making 3-7 turns; fertile cells scattered in twos or fours among vegetative cells, or continuous, inflated on the conjugating side, outer side straight; conjugating tubes formed almost wholly by the male cell, zygospores ellipsoid 37-42µ × 57-70µ, median wall minutely punctate, yellow. Type in herb. E. N. T. Coll. No. 2470, 2953.
This species was first found in the West Big Four Pond, east of Charleston, Illinois. It has since been found in a collection from Chocorua, N. H., sent me by Mr. Chas. Bullard. It evidently belongs in thepunctatagroup of the Spirogyras, but in form and markings of the spore, and the shape of the fertile cells it is amply distinct from its nearest allies;S. punctiformisTranseau and the next species to be described.
Cellulis vegetativis 30-40µ × 120-300µ, dissepimentis planis; chromatophoris singulis anfractibus arctis 3-8 cellulis fructiferis binis vel quaternis inter cellulas vegetativas distributis, inflatis et valde reflexis; tubo conjugationis ex cellula mascula emisso; zygosporis ellipticis, 44-54µ × 90-150µ, membrana media glabra et luteo-brunnea.
Vegetative cells 30-40µ × 120-300µ, with plane end wall; 1 chromatophore making 3-8 turns; fertile cells in groups of 2 or 4, inflated or enlarged and strongly reflexed; conjugating tube formed by the male cells; zygospores ellipsoid, 44-54µ × 90-150µ, median wall smooth, yellow-brown. Type in herb. E. N. T. Collection No. 2661, 2664, 2912.
This species has been under observation for four years and has been collected from ponds near Casey, Lerna, Coffeen and Donnellson, Illinois. The large, smooth spores, the reflexed conjugating cells, and the tube produced wholly by the male cells are the distinguishing characteristics.
Cellulis vegetativis 75-100µ × 210-360µ, dissepimentis planis, chromatophoris 7-10, modo subrectis longitudinalibus, modo spiralibus anfractibus arctis .1-.5; cellulis fructiferis inflatis vel subinflatis; tubo conjugationis ex cellula mascula emisso; zygosporis lenticularibus vel globoso-lenticularibus, 80-120µ × 110-195µ, membrana media scrobiculis obsita, brunnea.
Vegetative cells 75-100µ × 210-360µ, end walls plane, 7-10 chromatophores, either straight, or spiral making .1-.5 turns; fertile cells inflated or subinflated; conjugating tube formed by the male cell; zygospores lenticular or globose-lenticular 80-120µ × 110-195µ, median wall brown, pitted. Type in herb. E. N. T. Coll. No. 2661, 2665. Coffeen, Illinois.
This is one of the most remarkable forms described in this genus. It combines large size, the lenticular spore form, and the habit of forming the conjugating tube entirely by the male cell. The conjugating tube has walls heavier than those of any known species. Conjugation is both lateral and scalariform, and occurs between scattered cells, very rarely continuous for 6-8 cells. In the fruiting condition the filaments form a mesh-work which suggests the specific name. It has thus far been found only in the Fath Pond, north of Coffeen, Illinois.
A study of American specimens of this species from Massachusetts, Connecticut, New Jersey, Michigan and Illinois, shows that likeS. Grevilleanathere are always some cells with two chromatophores. I have twice found this species producing aplanospores.
P. B.-A. specimen No. 456, Easton’s Pt., Newport, R. I., belongs to this variety rather than the type, as shown by the scrobiculate spore wall. In Mr. Bullard’s collection there are also specimens of the variety from Pennannock, N. J., and from Spy Pond, Lake St., Arlington, Mass.
Cellulis vegetativis 24-30µ × 70-180µ, dissepimentis replicatis; chromatophoris singulis, rarius duobus, anfractibus arctis 2.5-6; cellulis fructiferis inflatis (ad 39-60µ); zygosporis ellipticis, polis plus minus acuminatis, 32-45µ × 48-93µ, membrana media glabra, lutea.
Vegetative cells 24-30µ × 70-180µ, end walls replicate; 1 (rarely 2) chromatophore making 2.5-6 turns; fertile cells inflated to 39-60µ; zygospores ellipsoid, ends more or less pointed, 32-45µ × 48-93µ, median wall smooth, yellow. Type in herb. E. N. T. Coll. No. 2955, 2956, 2957.
In Mr. Bullard’s collection there are specimens of this species from Lexington, Arlington, and Middlesex Fells, Mass. The P. B.-A. specimen No. 362, labeledS. Grevilleana, from Medford, Mass., belongs here, rather than toS. Grevilleana, in which the spores are distinctly ovoid with broad rounded ends.
This interesting form is characterized by quadrately inflated fertile cells, highly refractive cell walls, and unusually long cells and spores. In Mr. Bullard’s collection there are specimens from Stony Brook, South Framingham, Middlesex Fells, Wayside Inn, North Eastham, and Malden Fells, Massachusetts. The P. B.-A. specimen No. 363 labelledS. inflata, Orange, Conn., belongs to this species.
This species is one of several forms nearS. insignis(Hass.) Kützing. If Wille’s description is correct and identical with Hansgirg’s material, thenS. inconstansCollins becomes a synonym ofS. fallax. Hansgirg’s figure suggests that the filaments in his material are homosexual. While Wille’s description and figure suggests that the filaments are reflexed and that conjugation does not regularly occur between parallel filaments, with the spores all in one filament. It is difficult to decide just where these rough-spored forms belong as the earlier authors did not pay much attention to spore markings. In this connection the note by Professor Nordstedt in connection with specimen No. 958 in Wittrock and Nordstedt’s Algae Exsiccatae is of interest. Until these forms have been clearly separated by a study of the original collections it seems best to useS. fallaxforS. inconstans, of which the type is P. B.-A. No. 1568. Here also belongs P. B.-A. No. 1570, Middlesex Fells, Mass., and P. B.-A. No. 1571, Wakefield, Mass.
Cellulis vegetativis 56-66µ × 120-335µ, dissepimentis planis; chromatophoris 4-5, subrectis vel anfractibus arctis .5; cellulis conjugatis abbreviatis, inflatis (ad 135µ) et geniculatis; canalis conjugationis brevis et latis; zygosporis ellipticis, 75-105µ × 95-135µ membrana media glabra, lutea.
Vegetative cells 56-66µ × 120-335µ, end walls plane; 4-5 chromatophores, nearly straight or making a half turn; conjugating cells geniculate, shortened; fertile cells inflated up to 135µ; conjugating tube very short and broad; zygospores ellipsoid, 75-105µ × 95-135µ median wall smooth, yellow. Type in U. S. National Herbarium, collected by J. D. Smith, in S. W. Florida, March, 1878.
In its dimensionsS. floridanais intermediate betweenS. stictica(Eng. Bot.) Wille andS. ceylanicaWittrock. In several publications the statement is made thatS. ceylanicais intermediate betweenS. sticticaand the common forms ofSpirogyra. A study of authentic material of this species has shown that it has not intermediate characters, but with its spores having a minutely pitted median wall, it seems to be intermediate betweenS. floridanaandS. illinoiensisTranseau, the most specialized form in the Sirogonium group of the genus.
Throughout the study of these collections the writer has been greatly assisted by Mr. Hanford Tiffany, now a teacher in the Charleston, Illinois, High School. It is a pleasure to acknowledge my indebtedness to the many collectors who have sent me specimens for study.