288 NATHAN FASTEN. 



sixty of them may be counted (Figs. 34 and 35). These chro- 

 mosomes are about half the size of those found in the reduction 

 division (compare Figs. 34 and 35 with Figs. 27 and 28). As 

 for the chromatoid body, it generally lies at or near one pole 

 of the cell, leaving the other pole without any such element. 



The anaphase (Fig. 37) and telophase (Figs. 38 and 39) stages 

 follow each other in logical sequence, resulting in the division of 

 the secondary spermatocytes to form spermatids. Two types 

 of spermatids (Fig. 40), are thus formed in equal numbers; one 

 type which contains a single chromatoid body in the cytoplasm 

 (Figs. 40 and 41), whereas, the second type is without this body 

 (Figs. 40 and 43). 



D. Transformations of the Spermatids into Spermatozoa. 



The spermatids produced are, at first, small and their nuclei 

 contain large masses of chromatin material which stain intensely 

 with nuclear dyes (Fig. 40). The cytoplasm is homogeneous 

 throughout and within it a rather prominent centrosome is found. 

 In the second type of spermatid developed, the cytoplasm, in 

 addition to containing the centrosome, also possesses the chro- 

 matoid body (Figs. 40 and 41). 



The first noticeable changes undergone by the spermatids in 

 transforming into spermatozoa, occur in the nucleus. The 

 chromatin mass of the nucleus is gradually reduced to such a 

 degree that it loses its intense staining qualities, and becomes 

 quite homogeneous in consistency (Figs. 4047). At first the 

 large chromatin clumps break up into granular masses (Figs. 

 40, 43 and 44). Then these fragment still more completely until 

 in the final stages there remain, respectively, three round chro- 

 matin bodies (Fig. 45) ; then two (Figs. 42 and 46), and ultimately 

 one (Fig. 47). This remaining chromatin structure is spherical, 

 stains intensely black with Heidenhain's haematoxylin and occu- 

 pies the center of the nucleus. It may be said to be a nucleolus- 

 like body which resembles a karyosome. 



Both classes of spermatids produced undergo similar changes 

 of the nucleus. In the second type of spermatid, however, an 

 interesting change goes on in the cytoplasm, simultaneously with 

 the transformations of the nucleus. Here the chromatoid body 



