WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 63 



chromosomes upon the mitotic spindle of the first spermatocyte divi- 

 sion. The number thus appearing on the spindle is twelve (Plate 4, 

 fig. 39). One of them is the accessory chromosome, which is a dyad 

 and passes to one pole undivided (Plate 4, fig. 41, X). The eleven 

 tetrads represent the other twenty-two spermatogonial chromosomes 

 arranged in pairs. One daughter cell of each spermatocyte receives 

 eleven dyads and the other receives twelve, the additional one in the 

 latter case being the accessory chromosome. 



In the anaphase all the chromosomes appear as V's, thus showing 

 their dyad constitution (fig. 42 and 43). Before this, in the meta- 

 phase, the separate chromatids are not discei-nible, but early in the 

 anaphase they separate from each other at the end opposite that 

 which is attached to the spindle-fiber, in this way giving rise to the 

 V-shaped figures. The V-shaped arrangement persists until the 

 metaphase of the succeeding division is reached. 



3. Secondary spermatocytes. — The secondary spermatocytes pre- 

 sent only a short resting stage. For this stage, between the formation 

 of the secondary spermatocytes and their division, we may employ 

 the term interkinesis (intercinese) proposed by Gregoire ('05). The 

 extent of diffusion reached by the dyads in interkinesis is much greater 

 than that usually described for this stage, as will be seen from figures 

 46 and 47 (Plate 4). The djads reappear however, in the same 

 orientation and relative positions that they had before dift'usion. 



In the metaphase the dyads show the same double structure that 

 they did in the anaphase of the immediately preceding division (Plate 

 5, fig. 50-52). The two monads composing each dyad are separated 

 from each other in the metaphase, and in the anaphase are carried to 

 the poles of the spindle (fig. 54). Half of the secondary spermato- 

 cytes show in the plates of the metaphase eleven chromosomes and 

 the other half twelve chromosomes, as was to have been expected 

 owing to the non-division of the monosome in the division of the 

 primary spermatocytes. Figure 50 (Plate 5) shows eleven and 

 figure 51 shows twelve chromosomes. 



The term reductio^ial will be used to designate that one of the two 

 maturation divisions which results in the separation of the chromo- 

 somes that conjugated in synapsis. Correspondingly the term equa- 

 tional will be applied to the division in which the halves of whole 

 chromosomes are separated. Employing the terminology of Korschelt 

 und Heider ('03), we may use the terms prereduction when the first 

 maturation division is reductional, and postreduction when the second 

 division is reductional. 



