104 



CARNEGIE INSTITUTION OF WASHINGTON. 



THE SIGNIFICANCE AND CONTROL OF SEX. 

 Relation of Reproductive Overwork and Storage Metabolism of Ova to Sex. 



During the year Dr. Oscar Riddle has obtained new light upon the mechan- 

 ism of "reproductive overwork" (Whitman, Riddle) by the observation that 

 the suprarenal glands of female pigeons undergo marked and prolonged hyper- 

 trophy in very exact coincidence with each ovulation period (dehiscence of 

 two ova) ; and by the further observation that the carbohydrate metabolism 

 of the bird undergoes a simultaneous change, as shown by an increased con- 

 centration of the sugar of the blood. The data for the latter point were 

 obtained by Dr. Riddle with the cooperation of Dr. H. E. Honeywell, of the 

 Department of Physiology, Columbia University. Both of these results are 

 represented in curves, figure 1, which shows, in addition, that the oviduct 

 begins a pronounced temporary enlargement, and one or two ova begin a 

 period of extremely rapid growth, both coincident with the beginning of 

 hypertrophy in the suprarenals. 



Fia. 1. — Variation of weight of suprarenal gland, weight of oviduct, diameter of egg, and pro- 

 portion of sugar in the blood, before, during, and after ovulation. 



The data of the curve represent their first series of determinations only; 

 and, although later determinations have not given uniformly smooth results, 

 it is believed that the situation expressed by the curve has been satisfactorily 

 demonstrated. The curves for suprarenal size, oviducal weight, and dia- 

 meter of ovum were constructed from data obtained from 22 common pigeons; 

 the curve for blood sugar from repeated determinations on 5 healthy ring- 



