286 KANSAS UNIVERSITY SCIENCE BULLETIN. 



ZOOLOGICAL LABORATORY. 



chromosomes in the spermatogonia and twelve in the first 

 spermatocyte. In most cases where exceptions occurred it has 

 been found that they were only apparent, the full number in 

 each case being present, but with some two or three of the 

 members joined together, forming a multiple chromosome. 

 Stenohothrus, a form recently studied by McClung, has ap- 

 parently twenty-one in the spermatogonia and ten or eleven 

 in the first spermatocyte. The other exception is a sub- 

 family of the Acndidse, the Tettigidse. I have now on hand 

 slides of this form showing thirteen chromosomes in the sper- 

 matogonia and seven in the first spermatocyte. The variation 

 here need not, however, cause us worry, when we recall how 

 the Tettigidse differ from the rest of the Acrididse in external 

 characters. It seems more reasonable that they should be 

 considered a family by themselves, in rank equal with the Lo- 

 ciistidse, Gryllidx and the Acrididse, than as a subfamily of 

 the last group. The number for the family seems therefore 

 to be constant. Montgomery, however, seems to be in doubt 

 in regard to the number of the chromosomes in acuticoimis. 

 According to his observations some individuals have twelve, 

 while others of the same species have ten, and in the sperma- 

 togonia instead of twenty-three he finds but twenty. Being 

 unable to decide whether the two numbers in the spermatoc5i;es 

 ''were due to individual variation or to the presence of two 

 subspecies within the species," he chose to base his conclusions 

 upon the germ-cells of a single individual. It would have been 

 much better to have studied the cells of several individuals 

 and then to have made use of that merely which was typical 

 for the species. In the spermatogonia he "found only two 

 clear polar views of the metaphase, each showing twenty chro- 

 mosomes." Now the evidence furnished by two cells is not 

 enough upon which to base any important conclusion. There 

 is too much danger of not having the full number present that 

 belong in the cell. Very often a part of the number must be 

 sought in the next section ; or sometimes one or two which 

 may have happened to lie on the top or bottom of the section 

 have been dropped out or displaced. He has one other draw- 

 ing, a late anaphase of the last spermatogonial division, show- 

 ing the twenty, but at best any late anaphase is a doubtful 

 quantity. In the first spermatocyte he finds ten chromosomes, 

 but he has given not even a single drawing showing this num- 

 ber. 



