348 riddle: control of sex ratio 



— or one aspect of the differential which our own work has dem- 

 onstrated in the egg — is clearly continued in the blood of the adult 

 male and female. Fowls were substituted for doves in this 

 case in order to increase the size of the samples and thus increase 

 the accuracy of the analytical results. The blood of the male 

 contains less fat and less phosphorus — just as the male-producing 

 egg contains less of these same elements. The data further 

 show that the sexually active (or actively functional) females 

 depart most widely from the male, while sexually inactive females 

 occupy an intermediate position in respect of the amounts of 

 these constituents found in the blood (see Table 12). 



The results afford fairly clear evidence that in birds the meta- 

 bolic differences of male and female germs persist in the male and 

 female adults. 



In mammals too these aspects of sexual differences of the 

 adults have been fully demonstrated. Almost simultaneously 

 with the above determinations on birds, data were published by 

 Goettler and Baker ('16) which (as we have pointed out, '16) 

 show that the blood of the human male contains less fat, that 

 of the female more. Further, the basal metabolism of the human 

 male and female has recently been accurately determined by 

 Benedict and Emmes ('15) ; they find that the metabolism of man 

 is 5 to 6 per cent higher than that of woman. 



Have we any measure of either of our differentials in any 

 mammalian egg? I think that the experiments on sex-de- 

 termination in cattle, together with an observation by van der 

 Stricht, afford some evidence that the water content of the male- 

 producing egg is high, and that of the female-producing egg is 

 low. No one definitely knows whether the ovum of the cow 

 absorbs water in the Fallopian tubes in this interval between 

 ovulation and fertilization, but we do know that every amphib- 

 ian, reptilian, and avian egg that has been investigated does 

 absorb very appreciable amounts of water while being passed 

 from the ovary to the exterior. And van der Stricht has de- 

 scribed phenomena of growth or swelling of the yolk-granules of 

 one mammal — the bat — which, I am sure from my own studies 

 on yolk, indicate the taking up of water by the egg of this mam- 



