EARLY DEVELOPMENT OF HYDRA. 1 9 



swell the number of the minute spherules so plentiful in some 

 preparations. 



From the above accounts of the origin of the pseudo-cells it is 

 easy to see how, ranging as they do from exceedingly small to 

 very large ones, the conclusion might very naturally be reached 

 that they are products of the cytoplasm of the egg and grow 

 within it, undergoing certain changes in the process. Possibly 

 the metaplasmic bodies which have been described are derived 

 from the cytoplasm. It is not improbable, then, that some of the 

 darkly staining bodies, are, as Kleinenberg and others concluded, 

 accumulations or growths within the egg, but the majority, so 

 large that the process just mentioned may almost be disregarded, 

 are the remainr; or parts of the nourishing cells which are taken 

 into the egg, and, under certain influences undergo changes re- 

 sulting in a partial breaking down, and a characteristic disposition 

 of the elements composing them. These changes are not the 

 same in all coelenterate eggs in which pseudo-cells occur. The 

 hydroid eggs which I have examined {Tiibidarid) showed no 

 minute bodies at all. The pseudo-cells appeared to be derived 

 entirely from the nuclei of the nourishing cells. Possibly the 

 process here described may be found to occur only in periods of 

 excessive sexual activity when food is very abundant. 



Nematocysts within the Egg. 



In the early part of the paper it was noted that nematocysts 

 may become imbedded in the egg. In several preparations, par- 

 ticularly in the region near the supporting layer, there were found 

 oval bodies, apparently nematocysts, which were completely 

 covered with minute spherical granules. In some few cases a 

 suggestion of the filament within the nematocyst could be seen. 

 The shape and position of these bodies led to the conclusion 

 that they were nematocysts which were being absorbed or di- 

 gested. The nature of the granules covering their surface is an 

 open question. They may possibly have been digestive granules 

 of some sort. 



History of the Nucleus. 



The early history of the nucleus is difficult to follow. As 

 previously narrated, the egg begins its growth by the coalescence 



