SPERMATOGENESIS OF ASCARIS FELIS GOEZE 193 



The anaphase of the first spermatocytic division shows that 

 there is a shght lagging in the division of the hexad chromo- 

 some (fig. 6a) and that there is a distinct lagging in the progress 

 of the larger portion of the hexad towards the pole of the spindle 

 (fig. 6b) . The two daughter plates resulting from such a divi- 

 sion (figs. 7a and 7b) show that one received nine diad chromo- 

 somes while the other received eight diads and one larger tetrad 

 chromosome. Two types of second spermatocytes are thus 

 formed, one with nine autosomes and the other with the nine 

 autosomes plus the attached idiosome. The lagging during the 

 division of the hexad chromosomes was caused by the slow 

 response of the idiosome component, thus holding back the 

 division of the autosome member. The division is along the 

 plane of the transverse constriction of the autosome member 

 of the hexad chromosome and not at the point of union of the 

 idiosome and the autosome. The division is therefore qualita- 

 tive. The arrangement of the chromosomes in five cells in 

 which the idiosome was found separate from the autosomes 

 during the anaphase condition, support this interpretation, 

 inasmuch as the nine autosomes had divided without any signs 

 of lagging, and the idiosome passed undivided to one pole, but in 

 each case lagging behind its accompanying autosomes. 



2. Seco7id spermatocytes. The second division of the sperma- 

 tocytes containing nine diad autosomes (fig. 8a) is entirely 

 regular and quantitative, each spermatid receiving one-half the 

 amount of the chromatic material in the form of nine monad 

 chromosomes (fig. 10a). 



The second division of the spermatocytes containing eight 

 diads and one tetrad chromosome (fig. 8b) was also a quantitative 

 division in that each daughter plate received one-half the 

 amount of chromatic material in the form of eight monad auto- 

 somes and one diad heterochromosome (autosome plus idio- 

 some) (fig. 10b). This division shows the lagging reaction of the 

 idiosome in that the tetrad heterochromosome always separates 

 at one end (the autosome) before it does at the other (the 

 idiosome) (fig. 9a). The diad heterochromosome resulting 

 from such division always lags behind the autosomes in the 

 passage towards the poles of the spindle (fig. 9b). 



