24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



denser than ordinarily, and the meshes are filled with numerous granules 

 and globules of an oil-like substance. 



Cells showing these abnormal conditions arise at the extreme periph- 

 ery of the follicles only, and are usually separated from normal cells 

 of the same stage by numerous cells of a younger generation. The 

 explanation of these abnormal cases is, I believe, obvious. By the 

 too rapid propagation of the adjacent cells an inequality of pressure 

 has ensued, which has caused these cells to be forced to the periphery 

 of the testis instead of toward the centre, as ordinarily occurs. Here 

 they are nearer the base of food supply, and the consequence is a patho- 

 logical development, resulting in the hypertrophy of the chromatin and 

 the distortion and obscuring of the cytoplasmic structures. 



That these cells are abnormal or pathological is shown by their later 

 changes. Tliey never accomplish the spermatocyte divisions, but even- 

 tually degenerate. Such cells in diverse stages of degeneration may be 

 occasionally seen at various places in the testis and vas deferens. They 

 are eventually forced from their peripheral position by the pressure inci- 

 dent to the continued propagation of the adjacent spermatogonia. As 

 soon as they leave this position they always begin to show signs of 

 degeneration, if, indeed, such have not become evident before. The chro- 

 matin becomes granular and spongy, and no longer reacts to the stains 

 in a normal manner. As this retrogressive process continues, the cyto- 

 plasm decreases more and more and becomes loaded with the degen- 

 erating chromatin derived from the nucleus. This continues until a 

 division between nucleus and cytoplasm seems no longer to exist, and 

 the whole cell, much decreased in size, is filled with a dense mass of 

 granules which stain brown. 



The decrease in the size of the cell during these stages suggests that 

 it may possibly serve as food for the normal cells. Although this is 

 probably the case, I do not believe that certain cells are normally set 

 apart for this purpose. 



In following the later changes in the spermatocytes of Scolopendra, 

 it will prevent confusion if the two types are taken up and considered 

 in detail separately. In doing this I shall first give the history of the 

 changes in the large type, and next shall consider the small type, calling 

 attention to the points of similarity and difference, and attempting an 

 explanation of these differences. 



