698 C. E. McCLUNG 



ing the presence of a double cross division, and de Sinety and 

 Vejdovsky a double longitudinal division, must be recorded as 

 upholders of a mere substance relation between the chromosomes 

 of the two generations of germ cells. Wilcox and de Sinety fail 

 to effect a careful analysis of these relations and a detailed criti- 

 cism of their accounts will not be undertaken. 



Otte expresses his belief in the genetic continuity of the chro- 

 mosomes and describes a parasynapsis of spermatogonia! deriva- 

 tives in the first spermatocyte, and yet believes that there are 

 two cross divisions without any reduction. Vejdovsky, on the 

 contrary, from studies upon other Locustidae, argues for a com- 

 plete fusion of homologous spermatogonial chromosomes to form 

 a new mixochromosome, which is later divided twice longitudi- 

 nally. It is thus seen that the two recent workers upon Locustid 

 material, who doubt the occurrence of a reduction division, both 

 believe in the preservation of integrity of the chromosomes, but 

 in one case through a double cross division and in the other 

 through a double longitudinal cleavage. 



Opposed to these few contradictory advocates of doubtful or 

 impossible processes for the preservation of chromosome conti- 

 nuity are the large number who perceive and describe the only 

 possible means for ensuring it — through a temporary union of 

 homologous chromosomes and their later segregation in one of the 

 spermatocyte divisions. While there are differences of opinion 

 about the details of processes, there is agreement regarding the 

 end results. Always in some form the opinion is expressed by 

 the other students of Orthopteran spermatogenesis that because 

 of their organization the chromosomes may be identified in the 

 first spermatocyte as the descendants of the ones found in the 

 preceding spermatogonium. All find a pseudoreduction which 

 they ascribe to associations between the members of the diploid 

 group. There is a constant specific number and there are recog- 

 nizable, in most cases, either individual chromosomes, or groups 

 of thern, which may be traced from one cell generation to the 

 next. 



Criteria for such identifications are furnished by differences 

 in size, form and behavior and they apply with great exactness 



