100 PETER OKKELBERG 



he speaks of as a potency or valency. Now, it may be assumed 



that in a certain case the female factorial set, FF, has a value of 



80 units, and the male factor, M, a value of 60 units. The form- 



FF Mm FF MM 



ulae would then read as follows : ^^ _. = Female; „„ „„ , ^^ 



80 oO 80 oO 4- nO 



= Male. In the first formula the female set overpowers the 

 male set by twenty units, and in the second formula the male 

 set overpowers the female set by forty. According to Gold- 

 schmidt, two possibilities are open. Either the slightest prepon- 

 derance of one over the other, say only one unit, is sufficient to 

 determine the male or the female sex, or there is a necessary 

 minimum of preponderance beyond which only one or the other 

 sex appears. This minimum he speaks of as the epistatic mini- 

 mum. If the epistatic minimum be twenty; then when FF — M 

 is greater than twenty a female is produced, while if MM — FF 

 is greater than twenty then a male is the result. The intermediate 

 points represent the intersexes and, if they are heterozygous for 

 M, they are intersexual females, but if they are homozygous for 

 M, they are intersexual males. Definite races possess special 

 potencies for the male sex factors. A cross of races of similar 

 potencies gives normal offspring. Races of different potencies 

 of the male factors give female intersexes in the Fi generation 

 if the mother belongs to a race of lower potency''. The degree of 

 intersexuality depends upon the differences in the potencies. 



Another interesting case which seems to show that sex may be 

 disturbed by hydridization is that of the Norway rat when 

 hybridized with the albino rat. King and Stotsenburg ('15) 

 found a great excess of males among hybrid rats and came to the 

 conclusion '^ . . that hybridization alters the sex ratio by 

 producing a marked increase in the relative proportion of males" 

 (p. 110). Detlefson ('14) on the other hand, found a marked 

 preponderance of females, especially in the early hj^brid genera- 

 tions of the wild Brazilian guinea-pig and the conamon domestic 

 guinea-pig. 



Riddle ('16, and others) has conducted an important series of 

 experiments on sex behavior in crosses between the various 

 races of domestic pigeons. This work was begun by Professor 



