470 E. ELEANOR CAROTHERS 



2. Spermatogonial metaphases and female somatic metaphases 



a. Individual number 1. Dr. McClung ('14) has shown that 

 generally the point of spindle fiber attachment is constant in 

 all generations (spermatogonia, first and second spermatocytes). 

 Therefore, knowing the number of dyads in the first sperma- 

 tocyte with nonterminal fiber attachment, one would expect 

 to find the same number in the spermatogonia. The animal 

 represented on plate 1 has four Stenobothrus rings, each made 

 up of a pair of dyads with nonterminal fiber attachment or 

 eight such dyads in all; in addition, there are the atelomitic 

 dyads of the three J-shaped tetrads and the accessory; so that 

 we should expect twelve atelomitic chromosomes in the sper- 

 matogonia of this animal. Figure 1, plate 11, a spermatogonial 

 complex from this specimen, shows the twelve atelomitic chro- 

 mosomes. Entire complexes of spermatogonia were drawn in 

 order to be certain that all of the chromosomes with nonter- 

 minal fiber attachment might be present. The telomitic chro- 

 mosomes appear in outline only, as I wish to make the enumer- 

 ation of the others as easy as possible. 



b. Extremes found in the group. In order to show clearly 

 the correspondence between the spermatogonial chromosomes 

 and those of the first spermatocytes, two spermatogonial com- 

 plexes, one from Form 'A', the other from Form 'B', have been 

 rearranged so that the homologues are paired as they are in the 

 first spermatocyte anaphase (with which they are compared) 

 from the same individual. One of these spermatogonial com- 

 plexes is shown with the chromosomes in their normal position in 

 figure 32a (plate 11). The rearrangement of this complex may be 

 seen on plate 5, figure 32a. Fifteen atelomitic dyads are present 

 in both spermatogonium and first spermatocyte. Figures 36 

 and 63a' (plate 9) show similar arrangements of first sperma- 

 tocyte anaphase and spermatogonial complex, respectively. 

 Each has eight atelomitic chromosomes. Figure 63a' is a re- 

 arrangement of 63a (plate 11). 



From the analysis of the first spermatocyte metaphases, we 

 would expect animal number 62 to have the least number of 

 atelomitic spermatogonial chromosomes, . seven. This is seen 



