LITERARY NOTICES.

Mark Anniversary Volume. New York, Henry Holt and Company, pp. xiv, 513, 36 plates, 1903.

This volume, which contains in addition to twenty-five papers an excellent photogravure of Professor MARK, bears the inscription, "To Edward Laurens Mark Hersey Professor of Anatomy and Director of the Zoological Laboratory at Harvard University in Celebration of Twenty-five Years of Successful Work for the Advancement of Zoology from his former Students 1877-1902."

The following papers of the volume are within the scope of this Journal:

Locy, William A. A New Cranial Nerve in Selachians. Art. III, pp. 39-55

This research is a careful description of a new cranial nerve, homologous with PINKUS' nerve, in Squalus acanthias, Mustelus canis, Raja, Carcharias littoralis, Syphrna tiburo and Scoliodon terrae novae. Its existence has also been determined in embryos of Torpedo and in other selachians making in all 19 genera and 24 species of adults.

In all the forms described the nerve enters the brain in the median furrow, usually on the ventral surface of the (secondary) forebrain. In Squalus, however, it enters midway between the dorsal and ventral surfaces and in the skate on the anterior dorsal surface. The fibers are traced in the brain to a mesial eminence of the infolded pallium.

Peripherally the nerve is distributed to the nasal epithelium, the greater part going to the antero-lateral part of the olfactory cup. The exact termination was not ascertained. In some forms the nerve exhibits a ganglionic enlargement along its course.

Embryologically the nerve has its own independent connection. with the epithelium which precedes that of the olfactory nerve.

Locy is inclined to homologize the nerve with the new nerve described by PINKUS in Protopterus and by ALLIS in Amia-certainly the differences in point of connection with the brain would hardly justify one in seriously doubting the homology. Locy also thinks that "its separateness in origin and differences from all other olfactory radices" would justify its being called a "new nerve" even if it should prove to be an aberrant olfactory bundle. Apropos of this, the fact may be

mentioned that in the adult skate the writer of this criticism has observed a number of medullated nerve fibers in the nerve in question.

It is to be hoped that more information will be gained respecting the precise origin and termination of this nerve, also the precise nature of its ganglionic enlargements.

Reighard, J. The Natural History of Amia calva Linnaeus.

57-109, pl. 7.

O. S. S.
Art. IV, PP.

The very commendable general standpoint of this work was to study the natural history and especially the behavior of a fish in its natural habitat. Practically all the observations and experiments recorded were made in the field. That this method of working is necessarily a tedious and laborious one and produces results slowly will be apparent to everyone. The present paper stands as a model to show further that the method is capable of producing just as exact and detailed results as any laboratory work can, and of solving problems which never could be solved in the laboratory. The paper is not alone valuable as a considerable contribution to knowledge in a field where very little has been known, but also as an indication of the possibilities in work on the behavior of aquatic organisms in their natural environment.

Amia calva, the form chosen for study, is a fish which spawns in "nests." It was this habit which first aroused the author's interest in the subject, and the bulk of his work on the natural history of the fish has to do with its habits during the breeding season. A very careful, detailed description and analysis of its behavior during this period takes up the larger part of the paper. The nests are shallow circular areas on the bottom cleared of vegetation, and are built by the males, usually at night. Each nest is the property of a single male and is guarded by that male. If a female does not appear the male will finally abandon the nest. The spawning usually occurs at night and is intermittent. The females are not seen on the spawning grounds except when spawning. The behavior during the actual process of spawning is described. After the eggs are laid the male fish guards the nest until the larvae are about 12 mm. long. This stage is reached in about eighteen days, and at about this time the larvae leave the nest. While in the nest the larvae develop peculiar progressive swarm movements. The individual larvae aggregate in a closely packed group, which from a distance looks like a solid black mass. Within this swarm group individuals behave much as do Paramecia caught in a drop of weak acid. When an individual comes by chance to the boundary of the swarm it reacts and turns back into the swarm again.

"The larvae, though not progressing continuously as individuals, form a swarm which nevertheless progresses, one way and another, with many internal irregularities. The movement reminds one of the indefinite flowing movements of an Amoeba, in which pseudopods are put out this way and that and often withdrawn, but the animal as a whole progresses definitely." This swarm formation and movement is a most interesting phenomenon and presents a number of problems deserving of further study. Particularly interesting would be an experimental analysis of the reflexes and reactions of the individual larvae which result in the composite swarm effect when large numbers of individuals are massed together.

When the swarm of larvae leaves the nest it follows the male, apparently by scent. When separated from the male the schools of larvae do not make progressive movements as a whole, but circle about in the same spot until the male comes back. The larvae at this stage do not respond to a mechanical shock in the water, but at a later stage, when they have taken on bright colors and are from 30 to 40 mm. long, the schools respond very quickly to mechanical shock by scattering and hiding in the plant material at the bottom. The light reaction (negative to strong intensities) is more pronounced in the older, bright colored larvae. As the larvae grow larger the schools are less closely guarded by the males, and finally when they are about 100 mm. in length the schools probably disperse.

The paper is illustrated by a finely executed plate showing the coloration of Amia at three different stages in its life history.

R. P.

Eigenmann, C. H. The Eyes of the Blind Vertebrates of North America. V. The History of the Eye of the Blind Fish Amblyopsis from its Appearance to its Disintegration in Old Age. Article IX, pp. 167-204, pls. 12-15.

In this, the fifth of his interesting contributions to the subject, Professor EIGENMANN gives a detailed account of the development of the eye of the cave fish Amblyopsis. The eggs of this species are of large size and carried in the gill chamber until the embryos are 10 mm. in length. Egg bearing females were taken in March and April. The object of the research was to compare the development of degenerate and of normal eyes, and to determine (1) whether the development of the degenerate organs is direct or palingenetic, (2) whether there is a constant ratio between the extent and degree of phylogenetic and ontogenetic degeneration, (3) the causes leading to these degenerative changes, and (4) whether there is evidence that rudimentary organs are retained by the embryo because they are of use to it, although useless

to the adult. The stages of development of the eye are divided into four periods.

During the first period (from appearance of first protovertebrae to embryos 4.5 mm. long) the optic vesicle and lens are formed as in normal embryos, but there is retardation in cell-division and growth.

In the second period (embryos 5 to 10 mm. long) the optic nerve forms; its diameter is only 12 micra and it does not increase in size. The lens separates from the ectoderm but its cells do not differentiate into lens fibers and degenerate before the end of the period. A rudimentary iris forms from the margins of the optic vesicle; the cavity of the vesicle is practically obliterated, and the choroid fissure becomes a groove which may remain open. In the retina the pigment layers and inner reticular layer are developed; outer and inner nuclear layers are not differentiated, nor are the cones or dividing cells present as would be the case in the normal eye.

The third period (length from 10 to 100 mm.) is characterized by the degeneration of the nerve cells of the retina, the sinking of the eye to a position 5 mm. beneath the surface of the skin, the closure of the pupil and the complete disappearance of the vitreous body. Scleral cartilages show progressive development.

During the fourth period (fish more than 100 mm. long) the scleral cartilages become well developed and the eye muscles show no signs of degeneration. The pigment layer of the retina forms a thinwalled vesicle of considerable size while the nervous layer is less than 0.2 mm. in diameter and is markedly degenerate. In one individual observed the eye was completely disintegrated.

The author concludes "that there is no constant ratio between the extent and degree of ontogenic and phylogenic degeneration." From the rapid degenerative changes observed in ontogeny it is evident that the ultimate fate of the eye of Amblyopsis is total distinction.

The incomplete development of the eye is due (1) to retardation and final cessation of cell division; (2) to retardation of morphogenic processes; (3) to the extinction of histogenic activity. All three phenomena weaken as development proceeds. This may be caused. by external or internal influences. As, however, the eye remains degenerate in individuals reared in the light, and is well developed in other cave-inhabiting species, the factor of light may be eliminated. There is moreover, no evidence to show that atrophy is due to pressure from other organs or to lack of nutrition. It only remains to conclude that the causes of the degeneration are inherent in the ovum and are inherited by the embryo.

In discussing the law of biogenesis and the significance of rudimentary organs EIGENMANN points out that the eye is not retained by the embryo Amblyopsis because it is a functional organ at this stage, since during cave life the eyes are as useless to the young as to the adult.

C. W. P. Linville, Henry R. The Natural History of Some Tube-forming Annelids (Amphitrite ornata, Diopatra cuprea). Art. XI, pp. 227-235.

This paper gives a description of the tube-forming activities of the two annelids named in the title. Amphitrite constructs a U-shaped tube of mud and sand collected by the tentacles and held in place by mucus. The tube begins as a ring immediately behind the bases of the tentacles and the gills, and as the process of building is continued this ring is pushed backward by muscular action to make room for the materials which are brought by the tentacles. The author calls attention to the curious fact that this annelid is unable to reconstruct a new tube after the whole of its original tube has been removed. This he thinks, is due possibly to the absence of a stimulus from the tube which ordinarily initiates tube-repairing activities. The worm when young possesses an instinct which determines the construction of a tube, but this instinct after the formation of the first tube becomes valueless and disappears, hence when the animal is stripped of its tube it is unable to begin a new one. The presence of even a small portion of the old tube, however, is sufficient to initiate the appropriate tube-building actions.

Diopatra constructs a tube of sand, pebbles, bits of glass or any other material within reach. According to the observations of Dr. LINVILLE, it gives no evidence of selection of materials. The particles gathered are glued together with mucus secreted by the ventral glands. The animal first places a few pebbles in position then rubs the glands over them until they are firmly cemented. If, during the gluing process, the tentacles be touched with a piece of stone the process at once ceases, and the animal begins to gather material again. Thus the tactile stimulus determines the activity. The author mentions several interesting observations in connection with food taking and respiration.

R. M. Y.

Neal, H. V. The Development of the Ventral Nerves in Selachii. I, Spinal Ventral Nerves, Art. XV, pp. 291-313.

While this research by no means clears up definitely the much discussed question of the histogenesis of the peripheral nerves, it nevertheless is a useful contribution and will serve to deter many from ac.