DAVIS: SPERMATOGENESIS. 61 



the "accessory chromosome." In a later paper McCking (:00) gave 

 a detailed account of the spermatocytes and the maturation divisions 

 in Hippiscus (one of the Acrididae). He concluded that the first 

 maturation division is longitudinal, while the second is transverse, and 

 that the accessory chromosome, like the other chromosomes, divides at 

 both divisions. In the same year Sutton (:00) found that in the sper- 

 matogonia of Brachystola (one of the Acrididae) the chromosomes ex- 

 hibit a remarkable degree of separation, for during the telophase of 

 the secondary spermatogonial divisions each chromosome becomes en- 

 closed in a distinct vesicle. Later these vesicles fuse at their polar 

 extremities, with the exception of the one containing the accessory 

 chromosome, which remains distinct throughout the resting stage. 



In 1901 de Sinety, in an extended paper on the anatomy and physi- 

 ology of the Phasmidae, published an account of the spermatogenesis 

 of a number of Orthoptera belonging to several families. He con- 

 cluded that both maturation divisions are longitudinal or equational, 

 but that the accessory chromosome does not divide in the first divi- 

 sion. Thus only one half of the spermatids contain this chromosome. 

 A little later McClung ( :02^) , in an account of the spermatocyte divisions 

 of the Locustidae, confirmed de Sinety's account of the behavior of 

 the accessory chromosome during these divisions. McClung also 

 showed that during the spireme stage of the spermatocytes the acces- 

 sory chromosome becomes converted into a long coiled thread. His 

 account of the maturation divisions agrees with that previously given 

 by him for the Acrididae. Sutton (:02) in an interesting paper showed 

 that in the spermatogonia of Brachystola the chromosomes vary 

 greatly in size, but that with one exception, the accessory, there are 

 always two of each size, and that in the spermatocytes the bivalent 

 chromosomes have the same size relations. He believed that the 

 bivalent chromosomes were formed by the conjugation end to end of 

 the individuals of each pair of the spermatogonia. Sutton agreed 

 with McClung, that the second maturation division is the reducing 

 division. 



In 1902 Baumgartner published an account of the metamorphosis 

 of the spermatid in Grvllus, and later (:04) showed that in the sperma- 

 togonia the accessory chromosome forms a large V-shaped structure, 

 very different from the ordinary rod-shaped chromosomes. In the 

 growth stages of the spermatocytes the accessory chromosome forms, 

 as in the other Orthoptera, a deeply staining mass applied to the 

 nuclear membrane, and divides only during the second maturation 

 division. Baumgartner also believed that in the spermatocytes there 



