-56 INTERNAL SECRETION 



woman by reason of her generative glands. All the peculiarities 

 of her body and mind . . . everything, in fact, which in the true 

 woman we admire and revere as womanly, is dependent upon the 

 ovary." There are others (Geoffroy St. Hilaire, Klebs, Puech, 

 Hegar), however, who adopt a different view. Quite recently, 

 weighty arguments have been advanced by several authors 

 (Hegar, Halban, Pfliiger) against the dependence of somatic and 

 psychic sexual characteristics upon the genital glands. 



In order to grasp the precise significance of the problem, we 

 must first ask ourselves the question : What is the decisive factor 

 in the determination of sex? What is it which decides whether 

 from the fertilized egg, which contains both maternal and paternal 

 chromosomes in equal number, a male or a female individual shall 

 proceed ? 



It is possible that sexual distinction exists in the unfertilized 

 egg; that, in fact, there are male and female ova which, after 

 fertilization, develop in accordance with an already determined 

 sex. In certain of the lower forms of life this is actually the 

 case. Under certain favourable external conditions, the aphis 

 produces only females; at a low temperature with slight atmo- 

 spheric humidity, both males and females are produced, and 

 these pair. The pregnant female does not produce young, but 

 lays eggs, and from these, females are again hatched out. It is 

 evident that the sex of the individual is here determined in the 

 unfertilized egg. 



Korschelt showed that Dinophilus. apatris, a small worm, 

 lays eggs of two different sizes and that, from the larger of these, 

 females develop, while from the smaller, males proceed. Both 

 Nussbaum and Maupas found that, in the case of wheel- 

 animalculae (Hydatina senta), the larger eggs of which develop 

 into females and the smaller into males, the results were affected 

 by external factors acting on the mother, such as surrounding 

 temperature and nutritional conditions. 



A second method of ex differentiation, and one which recent 

 discoveries have shown in process of action, is by two distinct 

 varieties of spermatozoa. In certain insects, hemiptera and ortho- 

 ptera, two kinds of sperma cells are present, which differ from 

 one another in their chromosome contents. According to Wilson, 

 females proceed from eggs fertilized by cells with accessory 

 chromosome, males from eggs fertilized by the other cells.* 



In bees, ants and wasps the conditions are different, there 

 being only one kind of egg and one kind of spermatozoon. Males 

 are produced by parthenogenesis, females proceed from fertilized 

 ova. The queen bee is impregnated once only, the semen being 



* According to Omelczenko, Selenew and others, two kinds of sperma- 

 tozoon are also present in mammals and in man. Gram stains the body 

 of the one violet, of the second red. The two kinds of spermatozoon-bodies 

 are supposed to represent the two sexes. 



