1 36 MUNSON. [Vol. XV. 



kinesis, which follows in the ordinary way (PI. XIV, Figs. 



36, 37)- 



Unfortunately, notwithstanding the comparatively large size 

 of the nuclei in the earlier stages of this division process, the 

 spindles are small ; and the hyaline nature of the cytoplasm 

 renders it difficult to determine the conditions at the poles of 

 the spindle. The difficulty is further increased by the rather 

 peculiar phenomena of several contiguous cells seeming to divide 

 at the same time. Occasionally, single cells in the various 

 stages can be seen ; but, as a rule, a group of from four to 

 eight contiguous cells are in precisely the same phases of divi- 

 sion. The spindles seem to lie in all planes ; and the close- 

 ness of the elements renders it difficult to observe an entire 

 spindle with its two poles. Sections of the equators of the 

 spindles showing the chromosomes are numerous ; but the 

 confusion arising from the crowded condition of the elements 

 is such that any attempt at counting the chromosomes belong- 

 ing to a given spindle would not lead to reliable results. A 

 distinct centrosome imbedded in the accumulation of pro- 

 toplasm at one pole, however, has occasionally been observed. 



The stage with the greatly enlarged nucleus and the char- 

 acteristic chromatin thread is the most conspicuous one in 

 the process. These have been observed in most of the 

 ovarian tubes of young animals from five to eight inches, and 

 in material preserved in the nitro-picro-sulphuric mixture (see 

 methods), as well as in material preserved in Merkel's fluid. 

 In the latter material the thread is most beautifully preserved ; 

 while in the former the archoplasm and cytoplasm of the cell 

 are excellently preserved. 



As stated above, these cells usually occur in groups ; but 

 single cells, in this phase, can also be observed. The most 

 natural conclusion to be drawn in regard to the cause of these 

 cells occurring together in this way is perhaps that they are 

 the sister cells of an original mother cell ; and, being of equal 

 ages, they pass through the same cycle of changes at the same 

 time. 



In these groups of cells the large nuclei, occupying nearly 

 the whole cell, seem to lie closely applied to one another (PI. 



