136 PLAIN PACTS FOR OLD AND YOUNG 



nothing more than a revival of an old theory held by 

 physicians who flourished more than two thousand 

 years ago. 



Controlling Sex.— More recently another German 

 physician has advanced the theory that the sex may 

 be controlled at will by observing the time of fecunda- 

 tion. He asserts that when fecundation occurs shortly 

 after menstruation, the result will be a female; but if 

 impregnation occurs later in the month, and prior to 

 the three or four days preceding the next menstrual 

 period, a male will almost certainly be produced. This 

 theory was proposed by Professor Thury, of the acad- 

 emy of Geneva, who claims to have thoroughly tested 

 it in a great variety of ways, and always with an af- 

 firmative result. 



Floss, an eminent European author, claims to show 

 by a comparison of the statistics of male and female 

 births in various countries, that sex depends largely 

 upon the food supply, females being relatively most 

 numerous when food is abundant, while males pre- 

 dominate during periods of scarcity of food. Some 

 curious experiments were made a few years ago by a 

 learned entomologist, in the feeding of the larva of 

 insects, which seemed to indicate that those larva which 

 received the most food developed into females, while 

 those which had the least food developed into males. 

 Facts well known to bee-keepers also indicate that an 

 extra supply of food and better opportunities for devel- 

 opment, is possibly the principal cause which gives ori- 

 gin to sexually perfect bees from larva which would 

 otherwise produce ordinary workers. 



The facts just given would seem to support the 

 theory of Floss, but the equally eminent Dr. Preussen 



