530 P. W. WHITING 



Bending of the polar axis frequently takes place in anaphase, 

 and in telophase the daughter nuclei may become considerably 

 displaced relative to each other. Figure 28 represents a telo- 

 phase in which considerable bending of the polar axis has taken 

 place. The directions of the three main axes are therefore given 

 separately for each newly-formed nucleus. The chromosomes 

 still have their arrangement parallel to each other in each daugh- 

 ter nucleus. This is clearly seen at the right but not at the left, 

 as the equatorial axes are sloping. 



There is considerable tendency for the chromosomes to become 

 diffuse in anaphase, and in telophase this has gone so far that, 

 with normal staining by the iron-haematoxylin method, the 

 nuclei appear quite devoid of any chromatic material. The 

 slide from which figure 28 was taken was very darkly stained. 

 The telophase nucleus gives rise to that of the first spermatocyte 

 at the division of the cell body. 



c. First spermatocytes and nucleolar elements 



1. Earlier prophases. The character of the first spermatocyte 

 nucleus shortly after the last spermatogonial telophase is shown 

 in figure 29. The chromosomes are exceedingly tenuous and 

 the nucleolus is very diffuse, with four darker areas. Except 

 for its smaller size the nucleus resembles that of the spermato- 

 gonia as shown in figure 1. At a little later stage, as judged by 

 position of cysts, the nucleolus has condensed into two black 

 masses (figs. 30 and 31). Figures 32 a, 32 b, and 33 show later 

 stages in which the chromosomes are more condensed, nuclear 

 size considerably increased and nucleolus irregular and some- 

 what diffuse in parts. In figure 34 the nucleolus is very black, 

 but has a light centre. At this stage the nucleolus is always 

 very smooth in outline. Figure 35 is a characteristic condition 

 of a later stage in which the dark area of the nucleolus is sur- 

 rounded by a lighter granular investment. In figure 36 the 

 diffuse part appears to have been separated from the darker 

 part and forms a pair of terminal granules which are seen very 

 frequently in later stages. In figure 37 the nucleolus has become 

 diffuse, while the chromatic threads are thicker and darker. 



