ARTICLES 



S97 



This fits in well with the theory that in Mammalia the male 

 is heterozygous for the sex-determiner and the female homo- 

 zygous. 



In view of the very instructive results obtained from the 

 first family, the analysis of the second male-bearing strain 

 available was awaited with some interest. The result, however, 

 was disappointing, because only the descendants of one female 

 member could be traced, and thus the element of chance was 

 so considerable that no reliable deduction could be made. The 

 family is only included for the sake of completeness. 



Full analysis of Family 2 : 



The third family also showed too small a female line for 

 justifiable deduction to be made, and again is only included so 

 that all the six male-bearing strains found may be presented. 



Full analysis of Family 3 : 



Family 4, however, fulfilled all the requirements, and had a 

 satisfactory female line. It contained 177 members, and of 

 these 96 were males and 8 1 females ; thus having well over the 

 normal excess of males. The female line contained 41 males 

 and 47 females, and so approximated to the normal far nearer 

 than did the male line, which contained 55 males and 34 females. 



Full analysis of Family 4 : 



Found 

 Normal 



F. 



47 

 43-12 



This family, therefore, well supports the figures obtained 

 from Family i. 



Families 5 and 6, the last two suitable families found, show 



39 



