228 CHAS. W. HARGITT. 



been found. I have already directed attention to its entire ab- 

 sence during maturation also. Now it is interesting to find 

 abundant mitoses during the later cleavage, and during the growth 

 of the embryo. Is it not somewhat remarkable that among the 

 eggs of a given gonophore cluster in various stages of cleavage 

 and later embryonic development there should be found in certain 

 cases abundant mitoses while in others their entire absence ? This 

 cannot be attributed, under such circumstances, to differences of 

 fixation or other details of technique, for this has been identical 

 throughout. To what, then, may it be attributed, or how ex- 

 plained ? As already suggested in connection with the subject of 

 maturation, it seems to me we are forced to assume the operation 

 of some extremely obscure bio-chemical changes which neutralize 

 alike both acid and basic stains, or that certain phases of the mi- 

 totic mechanism may be disguised or actually lacking. 



In the light of cumulative evidences along this line I think one 

 may safely assume that the second of these alternatives is the 

 more probable, and the facts here submitted strongly support this 

 conclusion. 



During the earlier aspects of development the nuclear phenom- 

 ena associated with these eggs are extremely indefinite and obscure. 

 During maturation there seems to be an actual fragmentation and 

 dissipation of the nuclear matter throughout the cytoplasm. 

 The first signs of its reorganization appear in the segregation of 

 chromatin-like masses during the early phases of cleavage, about 

 which the cytoplasm becomes organized into cell-like masses, as 

 suggested in an earlier connection. At this time these chromatin 

 masses are extremely irregular in form and size, stain very 

 densely, and appear as indefinite, flocculent patches occupying 

 the center of cytoplasmic aggregates, or cells. They usually 

 assume an elongate, or often dumb-bell shaped form and seem to 

 divide amitotically, followed by the division of the cell. In Fig. 

 8 is shown a camera drawing of a section of an egg, in which 

 these features are evident. These are very common features 

 during this period of cleavage, and must, it seems to me, be re- 

 garded as more or less typical. In two of the cells of Fig. 8 

 will be observed typical resting nuclei. Whether this is prelimi- 

 nary to the beginning of the later aspects of mitosis I am unable 



