INCLUDING Dr. F. S. Conant’s Notes on the Physiology A DISSERTATION PRESENTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY E. W. BERGER BALTIMORE The Johns Hopkins Press 1900 PRINTED BY The Lord Baltimore Press THE FRIEDENWALD COMPANY BALTIMORE, MD., U.S.A. This Memoir is a continuation of the work upon the Cubomedusæ which was begun by the late Dr. Franklin Story Conant , and it contains his notes of physiological experiments, as w

This paper may be regarded as a continuation of the Cubomedusan studies pursued by Dr. F. S. Conant while in Jamaica, in 1896 and 1897, with the Johns Hopkins Marine Laboratory. His systematic and anatomical results have since been published as his Dissertation (“The Cubomedusæ”) by this University. Conant described this paper as Part I, hoping soon to add a second part on the physiology and the embryology, for which he had some notes and material at hand. Returning, however, to Jamaica with the

Light and Darkness —Experiments 1-9 , 10 , 33 , 34 .—As already stated in the Introduction, a part of Conant’s experiments were performed in a photographer’s dark-room, with the animals in a deep glass jar. In the dark a fair proportion of the animals became nearly quiescent on the bottom, but upon lighting a lamp many started up immediately, while others took a longer time to come to the surface and swim. These experiments were tried a number of times and on different occasions with very simila

Experiments 42-53 . Many of the observations on these forms relate to the rate of pulsation. In an Aurelia, following the removal of a lithocyst, there was a pause followed by pulsations. In about two minutes rhythmic pulsations were renewed. Four minutes after the operation there were nineteen pulsations to the half minute, while twenty minutes after there were only nine, and these in groups of six and three. The normal rate of pulsation was twenty-five to the half minute. Polyclonia behaved mu

Summing up for Charybdea, we have seen that it is very sensitive to light, strong light as also darkness inhibiting pulsations, while moderate light stimulates it to activity. Also, a sudden change from weaker to stronger light, or vice versa , may inhibit or stimulate to activity respectively. This behavior of Charybdea seems to be correlated with its habit of life on the bottom. We have no reason to doubt but that the eyes of the sensory clubs are the seat of light sensation. The experiments o

Light and Darkness. —1. Eight medusæ, in a deep glass jar and covered by a black coat, except one inch around the top, were placed in the dark-room. a. When light from a lamp was thrown on the surface (one inch) layer, the animals were active near the surface; when the light was withdrawn, one or two were on the bottom and not moving but were probably pulsating. b. After four or five minutes in the dark, three or four besides a feeble one are on the bottom. It took about two minutes to get them

[The following experiments were performed at Port Henderson, Jamaica, in 1896.] 42. May 12th. An Aurelia was pulsating normally at the rate of twenty-five or twenty-six pulsations to the half-minute. One lithocyst was cut out, when a few contractions, evidently caused by the stimulus of cutting, followed; then, rest. In the first minute there were only about five pulsations. In two or three minutes rhythmic pulsations were resumed. Four minutes after the cutting there were nineteen pulsations to

[The remaining experiments were all performed in 1897, at Port Antonio.] 49. Removal of the sixteen marginal bodies caused paralysis for a time; then recovery followed. Contraction was limited to the subumbrella. A portion of the subumbrella not from the margin can contract by itself as well as a portion of the margin with the marginal bodies (lithocysts). In the margin cut off as a strip with only one marginal body attached at one end, contractions sometimes started from the opposite end....

50. Size, seventeen or eighteen millimeters. Pulsations, thirty-two. Lithocysts, nine. The operation consisted in the removal of the concretions with as little injury to the pigmented parts of the marginal bodies as possible. One whole marginal body, however, was removed in the operation. Soon after the operation the pulsations were 28, 26, 20, 20, per minute. Another one; size fifteen millimeters. Pulsations were forty per minute. The operation consisted in the removal of the concretions and pi

The most important results in the histological part of this paper relate to the structure of the retinas of the eyes of the sensory clubs. The retina of the distal complex eye is composed of three kinds of cells: two kinds of sensory cells (the prism and pyramid cells), and the long pigment cells ( Figs. 1-9 ). The prism and pyramid cells have each an axial nerve fiber in their prisms and pyramids respectively. These fibers I could, however, trace only to the neighborhood of the nuclei. But sinc

I. Romanes , G. J. a. ’75, ’77. The Locomotor System of Medusæ. Philosophical Transactions. London. Vol. CLXVI, pt. 1. Vol. CLXVII, pt. 2. b. ’85. Jelly-fish, Star-fish and Sea-urchins. London. II. Murbach, Louis . ’95. Preliminary Notes on the Life-history of Gonionemus. Journal of Morphology. Vol. XI. III. Hesse, R. ’95. Über das Nervensystem und die Sinnesorgane v. Rhizostoma Cuvieri. Zeit. Wis. Zool., B. LX. IV. Eimer, Th. Zoologische Untersuchungen. ’74. Würzburg Verhandlungen. VI. Bd. V. H

1. Carrière, J. ’85. Die Schorgane der Thiere. München u. Leipzig. 2. Haake, W. ’87. Scyphomedusen des St. Vincent Golfes. Jen. Zeit. f. Naturwis., Bd. XX., pp. 596-597, 602-604. 3. Claus, C. ’78. Über Charybdea marsupialis. Arb. aus dem Zool., Inst. Univers. Wien., Bd. I. 4. Schewiakoff, W. ’89. Beiträge zur Kenntniss des Acalephenauges. Morph. Jahrb., Bd. XV, H. 1. 5. Patten, William. a. ’89. Studies on the eyes of Arthropods. II. Eyes of Acilius. Journal of Morphology. Vol. II. b. ’98. A Basi

A. Haeckel, E. ’72. Die Kalkschwämme. Vol. I, p. 141; Vol. III, Pl. 25, Figs. 3-5. B. Schultze, F. E. ’75. Rhizopodien Studien. V. Arch. Mik. Anat. Bd. II, p. 583. C. Eimer, Th. ’77. Weitere Nachrichten über d. Bau des Zellkerns, nebst Bemerkungen über Wimperepithelien. Arch. f. Mik. Anat. Bd. XIV, Taf. VII, p. 114. D. Bütschli, O. ’78. Beiträge zur Kenntniss der Flagellaten, u. s. w. Zeit. f. Wis. Zool. Bd. XXX, p. 269. E. Engelmann, Th. W. ’80. Zur Anatomie u. Physiologie d. Flimmerzellen Pflü

ALL FIGURES, UNLESS OTHERWISE STATED, ARE FROM CHARYBDEA. Fig. 1 . This figure represents a transverse section through a portion of the vitreous body of the distal complex eye at about the level x of Fig. 4 . Three kinds of areas are seen, namely, the prisms and pyramids with their axial fibers and the distal continuations of the long pigment cells. Towards the lower left of the figure the section is a little more distal than at the right and the transverse areas of the long pigment cells are no