SEX-RATIO OF THE DEER-MOUSE. 



141 



need not be long, since the correlation in question is decidedly 

 doubtful. The following table gives the sex ratios for mice be- 

 longing to broods containing from one to 7 (-f-) individuals 

 respectively, excluding broods in which individuals of unknown 

 sex are known to have died, and ones of probably mixed par- 

 entage (dual maternity). 



160 



ISO 



IfO 



130 



no 



100 



so 



ISO 



I 34567-3 



FIG. 6. Variations in the mean sex ratio, according to the size of the 



brood. 



