THE RELATIONS BETWEEN AMITOSIS AND MITOSIS. 1 93 



and close approximation in the spindle no data regarding the 

 direction of the two divisions could be obtained. 



As stated in the preceding section the spermatocytes often 

 appear in groups, the pear-shaped members of which are con- 

 nected at the pointed end by strands of cytoplasm. As the first 

 spindle forms the fusion of the cells proceeds (Fig. 18, PI. XI.) until 

 in many cases the metaphases of a number of nuclei lie in a con- 

 tinuous mass of cytoplasm, the cytophore (Fig. 19, PI. XL). Often, 

 however, the central region of the mass consists for a consider- 

 able time of a large space traversed by strands of cytoplasm (Figs. 

 1 8, 20, 23 (PI. XL), 25 (PI. XII.). The strands of cytoplasm are 

 represented in a somewhat diagrammatic manner.) In other 

 cases the first spermatocytes are entirely isolated (Fig. 21, PI. 1 1). 



The spindle appears to be formed largely from the nuclear sub- 

 stance. The fibers are very delicate and no asters are visible 

 (Figs. 1 8 and 19, PI. XL). At the poles are very minute, but 

 fairly distinct deeply-staining, centrosomes. In the masses re- 

 sulting from the fusion of several spermatocytes the spindles are, 

 so far as observed, always tangential or nearly so (Figs. 19 and 

 20, PL XL). Just before their division the dyads assume the 

 form seen in Fig. 22 (PI. XL), where one is viewed from the side, 

 the other from the surface. Fig. 20 (PI. XL) shows the ana- 

 phase. Division of the centrosomes has not been observed, as 

 they cannot be distinguished after the chromosomes have ap- 

 proached the poles. Fig. 23 (PI. XL) shows the telophase of the 

 first spermatocytic division in a group. The cytoplasm of the 

 cells which formed the group now constitutes a cytophore in 

 which the masses of chromatin lie. It is less dense in appear- 

 ance and stains less deeply than in earlier stages, where it was 

 concentrated about particular nuclei. The chromatin masses 

 remain at the periphery and the central region is often still more or 

 less vacuolated. Where isolated spermatocytes divide the result 

 is the same : no division of the cytoplasm follows nuclear 

 division, and a cytophore differing from the group-cytophore 

 merely as regards size is formed. 



The second division follows the first, in most cases apparently 

 without the formation of a " resting nucleus " between the two. 

 In a few cases, however, nuclei larger than spermatid nuclei and 



