Physiology and histology of the Cubomedusæ / including Dr. F.S. Conant's notes on the physiology

by E. W. Berger

I shall not endeavor to discuss the subject further, but shall append the literature on the subject that has come to my notice. (See [Literature]). Some of these observers ascribe a nervous function to these centrad continuations. I am inclined to believe that they represent the primitive fibrils of Apathy, whether the cilia or flagella are motile or sensory. I should mention, however, that Apathy has traced the “Primitivfibrillen” to be continuous with cilia, and also traces them into the sensory rods of the sensory cells in the sense organs of leeches. Eimer also describes cilia as continued centrad.

The Network Cells and the Multipolar Ganglion Cells.—Conant is the first to accurately describe the true structure of the network cells ([Fig. 13]) that fill the upper part of the club between the proximal complex eye and the attachment of the peduncle. I cannot add anything to Conant’s description. As their name implies, they are filled with a coarse network-like structure with a central nucleus and nucleolus. Schewiakoff erroneously described them as ganglion cells and Claus as supporting cells. I have sometimes thought that they are not made up of a network, but of a vesicular structure; i. e. the network we see is really produced by the sections of planes that intersect to form little polyhedral cavities. I could not, however, satisfy myself on this point. I further saw similar but smaller cells, with a finer network, disposed in small groups laterally and distally from the attachment of the peduncle to the club.

What the function of these network cells is can only be guessed. In size and shape they somewhat resemble some of the cells found in luminous organs. Conant, however, nowhere mentions that Charybdea is luminous.

Lateral to the larger group of network cells lie two groups of large multipolar ganglion cells (a group on each side). Claus describes these cells, but Schewiakoff does not specially note them, and evidently considered them a part of the network cells, which he erroneously described as ganglion cells.

The Nerve Tissue.—I cannot add anything new on this. It consists of fine fibers and ganglion cells, quite as described by Claus, Schewiakoff, and Conant, and fills the club between the ampulla and the epithelium, except the spaces occupied by the eyes, lithocyst, and network cells. It is likewise present under the ectoderm of the peduncle, where also a small tract is found under the endoderm. (See preceding head, or Claus[3], and Conant[8b]). As already noted, under the distal complex eye, I find only large nuclei to represent the ganglion cells. By saying this, however, I do not wish to dispute their ganglionic nature. The large multipolar ganglion cells I have noted under the preceding topic.

The Supporting Lamella.—The supporting lamella is a continuation, through the peduncle, of the jelly of the bell. It completely surrounds the ampulla and the lithocyst, and also forms a partition between them, so that, as already noted, the lithocyst becomes completely surrounded by it. It also sends a partition ventrally between the complex eyes (Figs. [7], [13]). Its thickening to form a support for the lens of the proximal complex eye has already been noticed. I shall limit myself in the discussion of the supporting lamella to the above short resumé, since Schewiakoff gives further detail.

The Endothelium of the Ampulla and the “Floating Cells.”—The ampulla is lined by a secreting epithelium. This is shown by the large masses of a secretion within the bases of the cells, and by smaller masses scattered in the central and more distal parts (Figs. [7], and [27], lower half). The section of the cells is such in [Fig. 7], that the bases of some (those nearest the supporting lamella) are taken, the central nuclear region of others, and the tips of those farthest from the supporting lamella. The section may be said to be taken diagonally through the bases and central parts of some of the cells, but owing to the curvature of the ampulla wall, through the tips of others. The secretion is a colloid substance, staining yellowish gray with iron-hæmatoxylin, blue with Lyons blue, and reddish with borax-carmine. Sometimes darkly staining rods and fibers of unknown origin could be seen within the larger masses of the secretion ([Fig. 7]). These rods and fibers could also be seen in spaces within the cells, from which the secretion had evidently been dissolved. I think there can be no question but that the masses described are a secretion. Many series, however, do not show it; indeed, an examination of Conant’s slides gave me little evidence of a secreting function, though I could demonstrate it in his sections both within the endothelium and also the floating bodies. The presence or absence of this secretion is evidently correlated with the feeding habits of the animals, or else it would be more generally present.

The endothelium is thickest (the cells are longest) in the upper part of the ampulla where the supporting lamella approaches the lens of the proximal complex eye, and in the lower portion of the ampulla ([Fig. 7]), in the angle between the concretion cavity and the region of the distal complex eye. In general, the cells are longest in the upper part of the ampulla, while in the lower part, especially where they cover the concretion cavity and the dorsal wall, they may be quite cubical instead of columnar. Often they present a vacuolated appearance at their bases ([Fig. 27]). Claus and Schewiakoff describe and figure this endothelium, but not in detail. No one, to my knowledge, has described this secretory function.

The nuclei of these cells are peculiar. They may contain a network with a nucleus ([Fig. 27]). Again, they may show evidence of amitotic division ([Fig. 20], h, i, j). Indeed, Remak’s scheme (Wilson[18] “The Cell,” p. 46) can be quite readily demonstrated. It is, however, such dumbbell-shaped, elliptical, or ringed nuclei as seen in Figs. [7] and [20] that are of special interest.