54 



" spermatocytes, in which the final step in the determination 

 " of sex is taken at the reduction of chromosomes. When 

 " this has been effected there remains nothing more to 

 " complete the cycle of the germ-cells than that they should 

 " form gametes, and this they usually do by two divisions." * 



Although it has long been known that some animals 

 possess two kinds of eggs, and that others possess two kinds 

 of spermatozoa, the second form in each — except in a very few 

 instances — has been regarded merely as a curiosity, or at most 

 as but a survival from some ancient and ancestral form. The 

 facts have, therefore, received but scant notice. 



The accepted view that there is but one kind of egg and 

 one kind of sperm finds its sanction and proof in their being 

 the products respectively of the female and male organisms. 

 Beard has shown, however, that the eggs and sperms are not 

 the products of the organisms bearing them, thus sanction and 

 proof both fail us and other facts must be sought. We have 

 already noted the fact that if two or more primary germ- 

 cells devolop normally their products are identical twins, 

 triplets, etc., including not only identity of form and feature, 

 but sex also. This in itself is significant. 



If it be true that there is but one kind of egg and one 

 kind of sperm, what is it that determines sex? It has been 

 estimated that during the past two hundred years some five 

 hundred different theories have been formulated to supply the 

 answer, every one of them, be it observed, based upon the 

 assumption of there being but one kind of egg and one kind of 

 sperm. Starting, as Beard has now shown, from a wrong base, 

 it is no wonder the solution sought gave rise to the legion of 

 theories. 



What, then, are the facts supplied by Beard which throw 

 new light upon this important subject ? Very briefly, then, 

 and of necessity ignoring very much that is pertinent and of 

 great interest, ignoring facts concerning hermaphroditism and 

 parthenogenesis, which under the newer light find clear and 

 reasonable explanation. 



' John Beard. " The Determination of Sex in Animal Development." Published 

 by Gust.av Fisaher. Jena. 1902. P. 707. 



