ORTHOPTERAN SPERMATOGENESIS 691 



results may be stated as follows: (1) There is constancy in num- 

 ber of chromosomes with differential sizes in a duplex series. 

 After the last spermatogonial division the chromosomes lose their 

 linin center and the naked chromatin threads of homologous 

 chromosomes fuse their substance to produce a new mixochromo- 

 some. (2) These mixochromosomes early split longitudinally 

 to produce dyads. Just before the first spermatocyte metaphase 

 these d^^ads again divide longitudinally to produce tetrads, 

 the largest of which are rings or ellipses. (3) These tetrads, by 

 slightly more concentration, pass into the metaphase where the 

 rings are large and conspicuous. (4) These rings are of the Sten- 

 obothrus type and lie parallel to the spindle axis. (5) In the 

 metaphase the annular chromosomes are reduced to half rings 

 by dividing across at their middle. (6) The fibers attach at 

 the centers of the half rings. (7) The anaphase chromosomes 

 resulting are double half rings or Vs. (8) As a result, the first 

 spermatocyte mitosis represents a longitudinal division. (9) In 

 the second spermatocyte the chromatids are separated along the 

 second longitudinal cleft. There are, therefore, two longitudinal 

 divisions and no reduction. 



c. Gryllidae 



Vom Rath ('91, '92, '95) has reported the process of maturation 

 in Gryllotalpa vulgaris, but, as stated in the discussion of the 

 spermatogonia, his results are so evidently erroneous that it is 

 profitless to attempt a comparison between them and the findings 

 of others. It is only necessary to mention, to indicate the char- 

 acter of his work, that he reported the diploid number of chromo- 

 somes to be 12 instead of 23, and that he entirely overlooked the 

 prominent accessory chromosome. For these reasons his work 

 will not be considered further. 



Gutherz ('07, '08, '09) in a series of papers on Gryllus has 

 discussed the behavior of the accessory chromosome and its rela- 

 tion to sex determination, but his work does not concern itself 

 closely with the problem.s of this paper. He notes the typical 

 behavior of the accessory chromosome during spermatogenesis 



