124 THE BIOLOGICAL PROBLEM OF TO- DA Y 



In one experiment, in which five females not yet 

 fully grown were kept in a room at the tempera- 

 ture of 26 to 28 degrees centigrade, Maupas found 

 that, of 104 eggs only 3 per cent, gave rise to 

 females, while in the case of other five young 

 females of the same brood, but kept in a cold 

 chamber at a temperature of 14 to 15 degrees 

 centigrade, 95 per cent, of females were produced. 

 In another experiment, young animals were kept 

 for a few days in the cold, and then, until death, in 

 a higher temperature. Of the eggs produced while 

 in the cold, 75 per cent, produced females, of those 

 deposited in the warmth, 81 per cent, became males. 



With these results may be compared what 

 happens with many plants. Melons and cucumbers, 

 which produce on the same stem both male and 

 female flowers, bear only male flowers in high 

 temperatures, only female flowers when subjected 

 to cold and damp. 



In the case of many insects in which partheno- 

 genesis occurs, the determination of sex depends 

 upon fertilisation. Thus, among bees, unfertilised 

 eggs give rise to drones, fertilised eggs to females. 



Sexual dimorphism in still another way reveals 

 the intimate interactions existing between all the 

 parts of an organism in every stage of develop- 

 ment. It is well known, for instance, that among 

 animals the early removal or destruction of the 

 sexual organs hinders the development of the 

 secondary sexual characters, or even may occasion 

 the appearance of the characters of the other sex. 

 Old hens become cock-feathered ; human eunuchs 



