PERIODICITY IN THE PRODUCTION OF MALES. 



195 



high nutrition (coupled with irregularities of nutrition). How 

 far his statement that the male-producing females are in the 

 larger families is correct, may be seen from Table VI., in which 



Table V. 



Showing Size of Family and Proportion of Male-producing (cf 9 ) and 



Female-producing (99) Females in a Single Line of Hydatina senta. 



Distinct from that in Table IV. 



the families of the starved line in the experiment referred to 

 (Shull, 1910, Table III.) are tabulated. The group of families 

 containing I to 5 daughters, and that of families numbering 41 

 to 45, are omitted because there is but one family in each group. 



Table VI. 



Showing Size of Family and Proportion of Male-producing (6^9) and 

 Female-producing (99) Females in a Starved Line ok Hydatina senta 

 Described in a Former Paper. 

 The greatest proportion of male-producers is in families of medium size. 



In this table it appears that the greatest number of male- 

 producing females is found, not in the largest families, but in 

 those of medium size. It may also be recalled that the distribu- 

 tion of the male producers with regard to size of family, in these 

 starved families where nutrition was known to have been variable, 



