Reproductive Processes of Sponges. 385 



In the future development of Spongilki the " transparent 

 spherical sac " and its contents, which have become developed 

 into an ampullaceous sac (" Wimperkorb "), appear to me to 

 grow into a gemmule or seed -like body (no. 6, p. 34), and 

 thus this increase or reproductive process to be successively 

 effected. 



That the " grain-like cells " of the transparent sacs do 

 pass into monociliated sponge-cells may be proved by taking 

 out some of the " yellow substance " on the point of a needle 

 and placing it in a watchglass with distilled water, when, 

 after a few days, the " grain-like cells " for the most part 

 disappear and are followed by a development of active mono- 

 ciliated sponge-cells (no. 3, p. 91, and no. 12, pp. 97, 98). 



Now comes the question whether the monociliated "sponge- 

 cells" of the ampullaceous sacs (" Wimperkorbe") are impreg- 

 nated by the spermatozoa for the formation of the seed-like 

 body, and the cells of the parenchyma or mesoderm for the 

 formation of the ovum respectively. 



When we reflect on the almost identity that exists between 

 the spongozoon or monociliated sponge-cell and the solitary 

 flagellated infusorium called " Salpingoeca" by the late H. 

 James-Clark, who first pointed out the resemblance (no. 9), 

 we can hardly help thinking that what the "solitary" form 

 possesses in the way of organs is equally possessed by the 

 social one or monociliated sponge-cell, and we can hardly doubt 

 that the solitary Salpingoeca and its like possess either an 

 hermaphroditic, monoecious, or dioecious system of reproduc- 

 tion respectively ; while, assuming that of the sponges to be 

 monoecious, the female organ or ovary must be looked for 

 either in the monociliated sponge-cells of the ampullaceous 

 sac (" Wimperkorb "), or in the unci Hated sponge-cells of the 

 parenchyma or mesoderm ; and if this be the case, then we 

 must consider the ampullaceous sacs in the marine sponges 

 (wherein there are no seed-like bodies) abortive in this 

 respect, and the ovum to be developed from the nutritive 

 sponge-cells of the parenchyma. And as there are swarm- 

 spores as well as seed-like bodies in SjyongtUa, both may 

 become impregnated and developed in their respective cells, 

 as already intimated, for the purpose of reproduction, in which 

 case impregnation would take place in the body of the sponge- 

 cell. How happens it, then, that Hackel has seen impreg- 

 nation of the ovum to take place in the parenchyma or meso- 

 derm ? Perhaps the ova may be thrown off from the ovary 

 of the parenchyma-sponge-cell in a very minute form, dis- 

 charged, and then transported into the intercellular substance 

 for increased growth previous to impregnation. 



