DEVELOPMENT OF THE EGG OF CLAVA LEPTOSTYLA. 223 



cytoplasm, another fact of which I can no longer doubt, then it 

 does not seem a far call to the assumption that the reduction 

 phenomena of maturation may well be accomplished without any 

 of the complex and spectacular processes of mitosis. Why should 

 the egg go through with the physical process of extruding the 

 polar globules if they are to be immediately resorbed by the 

 cytoplasm ? 



I do not overlook the circumstance that the opacity, and in 

 the present instance pigmentation, of the egg may establish an 

 obstacle so formidable as to render accurate observation ex- 

 tremely difficult, as I have previously admitted, still the fact re- 

 mains that carefully preserved and stained sections of hundreds 

 of eggs have failed to afford convincing evidence of the presence 

 of these bodies in distinguishable form, except in doubtful cases 

 already referred to. It would seem somewhat remarkable that 

 there should be all the differential results of staining upon other 

 cell features while it should be uniformly lacking in these, usu- 

 ally among the most readily demonstrated. 



Yet another feature bearing on this point will be found in the 

 details of cleavage, during which there is every appearance of 

 spontaneous nuclear reorganization throughout large portions of 

 the egg at almost the same time, the last detail of which may be 

 followed. The facts will be described in a later section, though 

 it seems well to call attention to their significance in relation to 

 the matter under consideration. 



CLEAVAGE. 



In a general way cleavage in these eggs corresponds with that 

 of other hydroids having similar gonophores, such as Tubularia, 

 Hydractinia, etc. The earlier work of Ciamician ('79), and 

 Brauer ('91), on Tubularia mesembryantkemum, and the later 

 work of Allen ('oo), on T. crocea, afford good examples of the 

 type of cleavage here referred to. In a recent paper ('O4 4 ), the 

 present writer has briefly reviewed the results of Ciamician and 

 Brauer, and it is unnecessary to discuss here in any detail these 

 features. Suffice it to say that Brauer found what he regarded 

 as two rather distinct types of cleavage. The first more or less 

 regular and equal ; the second irregular and indefinite, involving 



