DEVELOPMENT OF THE EGG OF CLAVA LEPTOSTYLA. 209 



almost certain that the vast majority of all egg-cells arise in the 

 gonophores themselves as, of course, is the case in almost all 

 free gonophores, or medusae, and as is invariably the case with 

 the spermatozoa. 



Therefore, while it may not be impossible that " urkeimzellen >: 

 should perhaps exist in undifferentiated stages, still the proba- 

 bility is so extremely remote as to render doubtful to a degree 

 any but the most thoroughly substantiated claims. 



It may be stated in passing, that the gonophores of C. lepto- 

 styla are extremely degenerate, hardly more, indeed, than sporo- 

 sacs, yet it is possible to distinguish rudiments of medusoid struc- 

 tures. They originate as buds of the hydroid, involving both 

 ectoderm and entoderm, and also supporting layer. Occasion- 

 ally this lamella seems to partially disintegrate at the terminal 

 portion during the outgrowth of the peduncle. The gonophores 

 remain entirely closed except at the time of rupture by the escap- 

 ing planula. From the primary peduncle secondary pedicels 

 arise, forming a racemose-like cluster, within each of which from 

 one to four eggs may develop, though the usual number is two 

 or three. 



There seems to be considerable variation in the size of the eggs 

 in various specimens and in the eggs of various gonophores of 

 the same specimen. On this point it had occurred to me that 

 perhaps the number developing in a given gonophore might 

 naturally have some influence, but after comparing a considerable 

 number, whether growing singly or in clusters I have not been 

 able to convince myself that such is the case. I am rather in- 

 clined to believe that more depends upon the. start a given egg 

 may get in growth, and perhaps the state of nutrition in which 

 the given specimen may be at the time, than any other factors. 



As a rule eggs which grow singly at the distal end of a gono- 

 phore are more nearly spherical, and in consequence I find the 

 cleavage of such eggs much more regular and symmetrical than 

 in cases where two or more are found in the same gonophore and 

 approach maturity at about the same time. This point may be 

 considered in more detail in a later connection under the subject 

 of cleavage. 



Growth takes place, as in most hydroids, quite rapidly. With 



