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THE AMERICAN NATURALIST [Vol. XLVII 



developed somatically in the male when either simplex 

 (Rr) or duplex (RR), but develops in the female only in 

 the duplex (RR) condition. The boars used were sim- 

 plex from their behavior in breeding, while the sows 

 embodied all three types. 



Kxprrtati..!! 



Fifteen of those recorded in the first two columns were 

 daughters of some of the remaining. In each case the 

 gametic composition assigned the young sows from their 

 breeding performance confirmed the formula assigned the 

 mother. There is some variation from the expectation 

 particularly in the female pigs from the RR sows and the 

 male pigs from the Rr mothers. The numbers are too small 

 to permit of the deviation being significant, however, and 

 the departure from expectation in the sow pigs in the 

 first instance shows that the rudimentaries are not a dis- 

 tinctly feminine character. Attention should be called to 

 the fact that in the male the deviations from expectation 

 are on the same side. 



The following table was plotted to see if the rudimen- 

 taries are a function of an increased number of mammae, 

 similar to the two common types of variation. 



The fluctuating percentages in connection with the fact 

 that the two lowest percentages are recorded against the 



