64 bulletin: museum of comparative zoology. 



4. Spermatids. — The spermatids, daughter cells of the secondary 

 spermatocytes, undergo gradual transformation, without further divi- 

 sion, into the mature spermatozoa. Their chromosomes undergo dis- 

 solution, having, however, first formed a network not unlike that found 

 in the telophase of ordinary mitoses. 



5. Spermatozoa. — This term is used, as usual, to designate the 

 functional male gametes — the end products of all the preceding 

 processes. 



c. Additional Features. 



In Phrynotettix, as pointed out by Pinney ('08), there appear in 

 many of the stages of spermatogenesis condensed and deeply staining 

 granules at the ends of the chromosomes. These granules are recog- 

 nizable in the stages where the greater part of the chromatin is ex- 

 tended or diffuse, so that their density, contrasted with that of the 

 rest of the chromatin, brings them into view. Figures 8, 10, 12 

 (Plate 1) and 14-20 (Plate 2) show them for the spermatogonia; 

 figures 28-38 (Plate 3) for the primary spermatocytes; figures 45-48 

 (Plate 4) for the inter kinesis stage, and figure 55 (Plate 5), for the 

 spermatids. These granules appear at that end of each chromo- 

 some — including the accessory — to which the spindle-fiber attaches. 

 They were named accordingly by Miss Pinney polar granules. In the 

 case of certain clu'omosomes, as noted by her, similar granules also 

 occur at the end of the chromosome opposite that to which the spindle- 

 fiber attaches. The chromosomes are thus seen to exhibit polarity 

 and it will therefore be convenient to designate the two ends by differ- 

 ent terms. In the. absence of better terms, I shall call the end to 

 which the spindle-fiber attaches the proximal or synaptic end, and the 

 opposite one the distal end. 



At various stages there is a tendency for some of the polar granules 

 to fuse together, as noted by Pinney '08, forming what I shall call 

 coviposite granules. These are to be seen in the telophase and pro- 

 phase of the spermatogonia (Plate 1, fig. 12; and Plate 2, fig. 14, 16), in 

 the spireme stages of the primary spermatocytes (Plate 3, fig. 33-36), 

 and even in the connective-tissue nuclei (Plate 9, fig. 108-110). 

 They are particularly noticeable in the pachytene stages, for during 

 that period quite large masses of chromatin may form by the coales- 

 cence of a nimiber of these polar granules. The number of granules 

 making up a composite granule is variable, but may usually be de- 

 termined by the number of spireme threads attached to it. These 



