. SPERMATOGENESIS OF ASCARIS FELIS GOEZE 195 



chromosomes of equal size and the larger X-type; the spermatid 

 receiving the Y-chromosome showed nine chromosomes, all 

 about equal in size. According to Boveri's interpretation, each 

 spermatid received nine autosomes, and the spermatids having 

 the eight small and the one large chromosomes really had an 

 X-type chromosome attached to one of the autosomes, thus 

 making it larger than the others. The other type of spermatid 

 did not receive any sex chromosome, therefore the chromosomes 

 were all of equal size. 



The present work has been based on a large amount of 

 material and, because of the occasional appearance of forms differ- 

 ing from the normal, has thrown additional light on the nature 

 of the sex chromosome complex of A. felis, thus showing that the 

 interpretation of Boveri was the more correct. 



The haploid number of the chromosomes is typically nine, 

 and the diploid undoubtedly would be eighteen, although po- 

 tentially the numbers are ten and twenty, respectively. Such 

 potential figures are probable because the independent initial 

 development of the idiosome, with only a secondary union with 

 an autosome, shows that there were, momentarily at least, 

 ten chromosomes in the early spermatocytic stage. This second- 

 ary union gives the haploid number of nine chromosomes, of 

 w^hich one is larger than the other eight. 



The behavior of the idiosome is that of an X-type chromo- 

 some rather than that of an XY- type for several reasons. Chro- 

 mosomes of the XY-type divide along their plane of syndesis 

 in the first division, and are each quantitatively divided in the 

 second. Chromosomes of the X-type are divided quantitatively 

 in one division, but are not involved in the other, although they 

 may be attached to the end of an autosome (Boveri, '09, and 

 Edwards, '10). The idiochromosome in A. felis is not involved 

 in the first division, passing unchanged to the second sperma- 

 tocyte. The plane of division passes through the transverse 

 axis of the autosome component of the heterochromosome, as 

 most clearly shown in the nuclei in which the idiosome failed to 

 become attached to an autosome, or was only partially con- 

 nected. In the former case the idiosome passed undivided to 



