112 PETER OKKELBERG 



SO that a prospective female develops male characters and a 

 prospective male develops female characters. Whether or not 

 complete reversal of sex has occurred in moths, does not appear 

 from literature on the subject, although there are apparently 

 cultures yielding nothing but males (Goldschmidt, '17, p. 605). 



In Bonnelia the sex metabolism is disturbed by envirorunental 

 conditions. This is also true in the case of Crepidula. In frogs, 

 delayed fertilization determines the results, as possibly also does 

 temperature to a certain extent. In rotifers the change may be 

 the result of the amount of oxygen present in the culture (ShuU 

 and LadofT, '16; ShuU, '18). Whitney, however, has obtained 

 different results with rotifers. From the various cases of sex 

 reversal in plants, mentioned above, it appears that in these 

 cases the change is effected by disturbing in one way or another 

 the normal conditions under which the plant lives. 



It seems to be amply proved that among dioecious animals 

 and plants every individual carries the qualities of the opposite 

 sex in a latent condition. This is a great step toward the solu- 

 tion of the problem of sex determination ; but it remains to explain 

 why in some cases one potency asserts itself, while in other cases 

 the other appears. Opinions on this question converge around 

 the conception of a variableness in cell metabolism and the 

 action of enzymes. Riddle thinks of male- and female-producing 

 eggs, in the case of pigeons, as different in regard to their storage 

 capacity — a less storage capacity pertains to the male — and a 

 high storage capacity pertains to the female-producing germ. 

 Riddle says: ''The progressive increase in storage capacity of the 

 eggs during the season — under overwork — is to be interpreted as 

 .a decrease in the oxidizing capacity of the same eggs." This 

 opinion is similar to that expressed by Shull in the case of rotifers. 



The metabolic capacity of the germ is, of course, reflected in 

 the adults derived from them; We can easily see how, in forms 

 like the lamprey, the storage capacity and the oxidizing capacity 

 may so nearly balance each other that every larva may exhibit 

 both tendencies in different parts of the body. This, as has been 

 suggested above, may be due to slight inequalities in the cells 

 resulting from division or to environmental factors of some sort 



