THE CHROMOSOMES 173 



with a pair of ordinary chromosomes. These pieces 

 have been supposed to be the sex chromosomes. 

 Their inconstancy and some apparent irregularity in 

 their distribution when the polar bodies are formed 

 has thrown some doubt on that interpretation. 



Perhaps more significant are the observations of 

 Kautsch and Geinitz on the number of chromomeres 

 into which the somatic chromosomes of Ascaris are 

 resolved. It appears in some individuals (females?) 

 there are about 8 more of these than in other in- 

 dividuals (males?). This relation might be expressed 

 as follows: 



52 chromosomes in male =22 + 8 (egg) + 22 

 (sperm) 



60 chromosomes in female = 22 + 8 (egg) + 22 + 

 8 (sperm) 



Kautsch has suggested that the 8 chromosomes are 

 attached at the ends of one of the pairs of chromo- 

 somes and are set free normally only when the 

 chromosomes break apart into their constituent 

 chromosomes. In the female two such chromosomes 

 would be present, in the male only one member of 

 the pair would have the attached part. The results 

 would then conform to the ordinary XX — XY 

 mechanism. The only objection to such a view is 

 that at an early stage the ends of the chromosomes 

 that go to the somatic cells appear to slough off. 

 If this involved the sex region, the sex determining 

 mechanism would be lost in the soma. T^ut there 

 is some evidence that the sloughing off does not 

 include essential elements of the chromosomes; for, 



