THE RELATION BETWEEN AMITOSIS AND MITOSIS. 



Fig. 54 (PI. XV.) represents a form of degeneration in cells 

 in prespireme stages which sometimes occurs in old testes. 

 Here the nuclei form irregular densely staining masses and finally 

 the whole breaks up and is absorbed. 



Fig. 55 (PI. XV.) shows degeneration of a group of spermatid 

 nuclei in a cytophore. The deeply staining granules and masses 

 in the nucleus increase in number, the nuclear membrane breaks 

 down, and the granules are distributed through the cytoplasm. 

 In Fig. 56 (PI. XV.) another form of spermatid degeneration is 

 seen and a later stage in Fig. 57 (PI. XV.). Fig. 58 (PI. XV.) 

 represents a still later stage : vacuoles usually containing a single 

 granule still indicate the position of the nuclei ; the mass stains 

 only very faintly at this stage and seems to decrease gradually 

 in size until finally it becomes imbedded in a cytophore and 

 gradually disappears. 



Fig- 59 (PI- XVI.) represents a form of degeneration of the 

 spermatids which usually occurs only after the spermatozoa have 

 begun to develop. About the periphery of each nucleus a large 

 amount of deeply staining substance develops and appears to 

 flow toward the center of the cytophore. In Fig. 60 (PI. XVI.) 

 is shown a later stage of this form of degeneration. Here the 

 cytoplasm stains rather more deeply than that of the normal 

 cytophore, the deeply staining substance has disappeared entirely 

 from the peripheral regions except in a few radiating strands and 

 the positions of the nuclei are indicated only by vacuoles. In 

 still later stages (Fig. 61, PI. XVI.) the deeply staining substance 

 gradually breaks up into granules (Fig. 64, k, PI. XVI.), loses its 

 staining power and finally disappears, and the whole cytophore 

 becomes highly vacuolated, breaks up into irregular masses and 

 shreds (Fig. 64 /, PI. XVI.) and is apparently absorbed. 



Other modifications of the process of degeneration are occa- 

 sionally seen but these are the principal ones. The apparent 

 variation which these processes exhibit is of some interest as 

 indicating that differences in the processes of degeneration like 

 differences in development are undoubtedly determined by differ- 

 ences in the condition of the cells or of the environment. At 

 present, however, even a surmise as to the nature of these dif- 

 ferences is of little value. 



