riddle: control of sex ratio 



347 



ber of data bear'ng on adult sexual differance of the sort we 

 most require are already at hand. 



Turning now to the diagram we note that egg and adult stages 

 are first distinguished. In the egg of the pigeon we have iden- 

 tified maleness and femaleness by three differentials. Female- 

 ness in the egg-stage being accompanied by low metabolism, 

 lower percentage of water, and higher total fat and phosphorus, 

 or of phosphatides. Maleness is here accompanied by high 

 metabolism, higher percentage of water, and lower total fat and 

 phosphatides. Now there are valid reasons for treating these 

 three differentials not as separate and disconnected facts, but 

 rather as aspects or corollaries of the same fact. For example, a 



TABLE 12 



Sexual Differences of Fat and Phosphorus in the Blood of Adult Fowls 



and of Man 



Males (roosters) 



Non-laying females 

 Laying females 



Males (man) 



Females (women) . . 



AVERAGE 

 TOTAL FAT 



15.45 

 17.87 

 27.80 



AVERAGE 



TOTAL 



PHOSPHORUS 



6.43 



7.42 



13.15 



RELATIVE 

 AMOUNTS OF 

 PHOSPHORUS 



100 

 115 

 205 



141.4 

 226.0 



high metabolism in a cell is consonant with less storage of fat and 

 phosphatides, and with a more highly hydrated state of the cell- 

 colloids. It follows that where data for either of these three 

 differentials are at hand, for either the germ or adult of any ani- 

 mal, we have in such data evidence of the kind we r are looking 

 for, i.e., evidence for the association of a given type of metab- 

 olism with the germ or adult of a given sex. 



For what forms then are such data available? t And, what is 

 now known of the persistence of this definite type of differentia- 

 tion of the two kinds of sex germs into adidt stages of the two 

 sexes? Recently, in my laboratory in cooperation with Mr. 

 Lawrence ('16), it has been shown that one of these differentials 



