THE NUTRITION OF THE OVUM OF HYDRA VIRIDIS. 



WM. A. KEENER AND J. B. LOOPER, 

 UNIVERSITY OF VIRGINIA. 



The incipient ovary of Hydra viridis is represented by a mass of 

 proliferated interstitial cells. At a very early stage in the de- 

 velopment of the ovary some of its cells become much larger than 

 the others. There seems to be a struggle on between these cells; 

 for, as development of the ovary proceeds, but one of the larger 

 ones remains whole, and the smaller ones perish. The cells, that 

 are directly involved in this struggle, are enclosed in a thin wall 

 of slightly chromatic, modified epithelio-muscular cells. Kleinen- 

 berg (72), Brauer (91), Downing (08) and Tannreuther (08) agree 

 in the statement that one of the enlarged interstitial cells gets 

 the ascendency over the others and grows at their expense. If 

 there be in the incipient ovary more than one greatly enlarged 

 interstitial cell, these may fuse to form the oogonium as over 

 against the cells of what Tannreuther (08) designates "the cells 

 of the peripheral region which contribute to the formation of the 

 yolk," p. 274. These peripheral cells are not taken into the 

 growing oogonium's cytoplasm bodily as Brauer (91) described. 

 They disintegrate at the periphery of the oogonium and are then 

 resorbed. The relation of these disintegrating cells to the cyto- 

 plasm of the final oogonium are shown in Fig. i . Figs. 3 and 4 

 show phases of disintegration in these neighboring enlarged 

 interstitial cells. As their cytoplasm breaks down, the nuclei 

 display disintegration features. Eventually the entire cell dis- 

 integrates. The substance of these disintegrated cells is absorbed 

 by the oogonium, as Kleinenberg (72) described. The material 

 thus obtained results in the oogonium growing greatly to become 

 a conspicuously large amoeboid cell (Text-figure 2). This cell, by 

 means of radiating stout pseudopods, spreads out over one third 

 or more of the mesoglea's outer surface. This amoeboid gamete 

 was first figured by Fewkes and Mark in 1884. This pseudo- 

 podial cell has now attained its maximum size and is, therefore, 



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