244 WM. REES B. ROBERTSON 



197) has, in addition to the long sex chromosome, fifteen rod 

 tetrads, plus the V (14, 14, 16, 16) with limbs double the length 

 of the spermatogonia! V. This V showed considerable inequality 

 in the lengths of its limbs; moreover, there were constrictions 

 (figs. 198, 199) at the middle of each limb, indicating the points 

 at which separation in the last stage of disjunction is about to 

 take place. It is probably a bi-tetrad, for, counting it as such, 

 we get the seventeen tetrads characteristic of the first spermato- 

 cyte. Anaphases (Woolsey, '15, figs. 44-47) proved that separa- 

 tion did take place at the points of constriction on the double- 

 length arms of this V bi-tetrad. To one pole went a V with 

 unequal arms, similar to the spermatogonial V; to the other 

 pole went two rods of unequal length, similar to the limbs of 

 the V from which they had separated. I can think of no clearer 

 demonstration than this, that, in so far as these chromosomes 

 are concerned, the first division is reductional. The remaining 

 fifteen tetrads behave in all respects similar to the limbs of the 

 bi-tetrad V (figs. 195, 198, 199). In view of the fact that this 



V separates from its rod-mates (fig. 199) and that in the two-V- 

 chromosome of the first spermatocytes (fig. 201) of another spe- 

 cies (J. unicolor) the V's open out into an unequal-sided ring 

 of the same size as the bi-tetrad V of the first species (J. sub- 

 guttata), there is strong reason for believing (1) that the three 



V pairs of Chorthippus likewise divide reductionally in the first 

 maturation division; also (2) that all perperidicular rings of first 

 maturation divisions resulting from V pairs of chromosomes 

 are of a similar nature, dividing reductionally. Furthermore, 

 since the limbs of the long V bi-tetrad (figs. 197-199; Woolsey, 

 '15, figs. 39-43) are similar in every respect to the other tetrads 

 present, I suspect that this division is reductional for all of the 

 pairs of chromosomes in this genus. 



A third case that forces me to take sides in favor of pre-re- 

 duction is that of the separation in the first maturation division 

 of the members of unequal homologous chromosome pairs, 

 such as I found (Robertson, '15) in one specimen of Tettigidea 

 parvipennis (figs. 115, 120, 122, no. 4's) and in one specimen 

 of Acridium granulatus (figs. 141-147, no. I's). From a study 



