m'clung: spermatogenesis of XIPHIDIUM FASCIATUM. 261 



I consider the work of Otte entirely erroneous so far as it 

 relates to the method of division of the accessory chromosome 

 in the second spermatocyte mitosis, for it is widely at variance 

 with what I have found in the large number of species of the 

 Orthoptera that I have examined. The figures that he pre- 

 sents in his preliminary paper ('06) are not at all convincing, 

 and I am fully persuaded that a more thorough study will con- 

 vince him that his identification of the longitudinal split of the 

 accessory chromosome in the second spermatocyte metaphase 

 with the space between the bent halves of the rod in the pro- 

 phase of the first spermatocyte is a mistake. That Otte's in- 

 terpretation could not apply to Xiphidium is evident from an 

 inspection of the second spermatocyte during the division of 

 the accessory chromosome (fig. 17). The element here is in 

 the shape of a V with the fibers attached at the angle. It is in 

 this form that Otte conceives the break across the rod to occur, 

 but instead the whole bent structure is split along its length 

 into duplicate V-shaped halves. There is no possibility of mis- 

 taking the longitudinal split for a space between the halves of 

 a bent rod. In those forms where the fibers attach at the ends 

 of the chromosomes there would be more of a possibility of 

 such confusion, but even there a sufficiently complete series of 

 stages will make clear the presence of the longitudinal cleavage 

 and its identity with the plane of separation in the second 

 spermatocyte metaphase. 



It is unnecessary to point out that Otte's account does not 

 agree with the great majority of observations upon other forms, 

 and that, on the theoretical side, it attacks the hypothesis 

 of the individuality of the chromosomes, unless indeed he would 

 assume that the accessory chromosome is bivalent. It is very 

 probable that he does not make this assumption, for all the 

 other chromosomes are described as being transversely divided. 

 So far as I know, the only writer who regards the accessory 

 chromosome as bivalent in the Orthoptera is Montgomery, who 

 made a superficial study of this structure in Syrbula, an 

 acridian. That he is in error on this point is shown by the 

 work of Robertson (in publication) upon the same genus. 



2-Univ. Sci. Bull., Vol. IV. No. 11. 



