404 



SCIENCE 



[N. S. Vol. XLI. No. 1054 



males; 13 males to 38 females, i. e., 25.49 per 

 cent, males to 74.51 per cent, females (sex 

 ratio 34.21). 



To determine further whether the sex-tend- 

 ency of males showed any inclination to change 

 from mating to mating the records were 

 counted in the following manner : 



Taking the matings of given males follow- 

 ing matings that produced only female young, 

 it was found that the product of such matings 

 consisted of 22 males to 27 females, i. e., 44.90 

 per cent, males to 55.10 per cent, females (sex 

 ratio 81.48). 



Taking the matings of given males follow- 

 ing matings that produced only male young, 

 it was found that the product of such matings 

 consisted of 28 males to 24 females, i. e., 53.84 

 per cent, males to 46.16 per cent, females (sex 

 ratio 116.66). 



This result is therefore the reverse of that 

 shown by the females. Whereas the females 

 show an opposite tendency following each 

 litter, the males always maintain the same 

 tendency. 



Only those litters which were purely male 

 or female were used in the above considera- 

 tion. After a mixed litter of males and fe- 

 males, which is more common under natural 

 conditions, there is not a pure, but also a mixed 

 sex tendency. This fact renders the recogni- 

 tion of the " C " factor extremely difficult. 



Such a characteristic change in tendency 

 from birth to birth also seems to occur in 

 other animals. The daplmids, for instance, 

 seem to have some such regulation very defi- 

 nitely expressed.'- In these organisms also the 

 sex tendency changes from generation to gen- 

 eration as well as from birth to birth in such 

 a way that not after each generation and each 

 birth, but after a number of generations and 

 births, differing with different species, the ex- 

 clusive production of parthenogenetic female 

 ceases and the first males appear. Doubtless 

 we have in this an example of a change of the 

 sex tendency, but its expression is quite differ- 

 ent from that in the guinea-pigs. 



1 Papanicolaou, G., " Experimentelle Untersueh- 

 ■ungen fiber die Fortpflanzungsverhtiltnisse der 

 Daphnideu," Biol. ZentralU., 30, 1910. 



From a theoretical standpoint, it is very 

 important that coincidentally with the change 

 of sex tendency in the summer eggs from 

 female to male in Moina rectirostris var. 

 Lilljeborgii, there is also a change in the color 

 of these eggs from violet to blue.- This fact 

 probably indicates that some chemical change 

 occurs in the eggs at the same time that the 

 change in the sex tendency takes place. 



At the present time I am endeavoring to 

 complete my observations and to determine 

 statistically the relative value of the three 

 factors in different combinations. Since, how- 

 ever, the animals at my disposal are designed 

 especially for the study of the degenerative 

 influence of alcohol, it will, no doubt, require 

 a long period of time to collect hundreds of 

 selected cases, since so few animals of the 

 generations later than the third are capable of 

 reproduction. 



This preliminary report is published with 

 the hope that other investigators, having a 

 large stock of different animals at their dis- 

 posal, may further contribute to the solution 

 of this problem in all its details. 



George Papanicolaou 



Depaktment of Anatomy, 

 Cornell University Medical College 



THE AMEMICAN ASSOCIATION FOB THE 

 ADVANCEMENT OF SCIENCE 



section c 



The first session, was held on the afternoon of 

 Thursday, December 31, at the John Harrison Lab- 

 oratory of Chemistry, Vice-president Edgar F. 

 Smith in the chair, with an attendance of about 

 75. The following officers were elected: 



Vice-president — William McPherson, Ohio State 

 University. 



Member of Council — W. T. Taggart, University 

 of Pennsylvania. 



Member of General Committee — L. W. Jones, 

 University of Cincinnati. 



Member of Sectional Committee — E. C. Pranklin, 

 Stanford University. 



The section passed a resolution to the following 

 effect: That the committee of Section C endeavor 



2 Ibid. 



