256 A. RICHARDS. 



formation of chromosomal vesicles in the anaphases of ova has 

 not been a matter of infrequent observation; and this phe- 

 nomenon is not commonly seen in cells other than egg cells. In 

 other words, the formation of chromosomal vesicles is, without 

 much doubt, correlated with the presence of an unusually large 

 amount of cytoplasm. As the chromosomes are transformed 

 into vesicles, they absorb, it seems, large amounts of the achro- 

 matic material from the cytoplasm, by which they grow to 

 resemble the familiar reticular structure. Their true nature 

 becomes masked, but as will appear later, is not really changed. 

 Vesicular chromosomes have been described in fish eggs by 

 Moenkhaus and certain of the figures of Miss Morris indicate 

 that she also saw them. 



According to the usual interpretation, and to this Moenkhaus 

 subscribes, the individual vesicles fuse with their neighbors and 

 these larger ones with each other until at last the entire nucleus 

 is simply one great vesicle. Moenkhaus describes the trans- 

 formation of the chromosomes into resting nuclei as taking place 

 by their conversion into vesicles which during an early stage 

 can be distinguished into two groups by the difference in size. 

 Then the smaller vesicles "fuse at first into larger ones, giving 

 rise to a lobed nucleus. At this state it is no longer possible 

 to tell the two kinds of vesicles apart. The fusion continues 

 until a single well rounded nucleus results, with all traces of its 

 double character lost." 



Increase in size of the chromosome continues through the 

 telophase stages and to the resting stage. A rough calculation 

 of the growth from the stage (Fig. 7) where the definite vesicular 

 character of the chromosomes (late anaphases and early telo- 

 phases) is first discernable to the full size found in resting nucleus 

 (Fig. 12) indicates a fivefold increase. It is scarcely possible to 

 compare quantitatively the amounts of chromatin in the con- 

 densed chromosome and in the disperse vesicular stage. But 

 one cannot easily doubt that an actual increase has taken place 

 in the latter case. It is during this time in all probability that 

 the new chromatin is formed in preparation for the ensuing 

 division; and at the same time growth in the amount of achro- 

 matic substance present would also take place. The swelling 



