616 SIDNEY I. KORNHAUSER 
to develop into gametes of the opposite sex (Chapin, 717). This 
stability exhibited by the germ cells is probably due to some 
fundamental difference early established in the evolution of 
sex between spermatogonia and oégonia or between spermato- 
cytes and odcytes. 
Were it permissible to speculate upon the origin of the sexual 
differences, the writer would consider the production of two 
sorts of gametes as the first and fundamental step. It would 
be assumed that originally either in the protozoans or lowest 
metazoa the individuals were isogametic and that zygotes were 
formed by the union of two similar, rather large, and not. ex- 
tremely active gametes, as still exist among many green algae 
and certain protozoa. If by a mutation one individual pro- 
duced many small, highly motile gametes which sought the 
larger less active ones in conjuguation, the number of zygotes 
might be increased and the species thereby benefited. This 
original mutation which established microgamete production 
would require a more rapid cell division and a shorter growth 
period in gametogenesis. The gene bringing this about would 
be represented in the constitution of all the cells of the individ- 
ual, somatic as well as germinal, and might influence in many 
ways the form and physiology of the whole individual. Recently 
Morgan (717), in speaking of the manifold effects of each gene, 
citing an example from Drosophila, says that, ‘‘whatever it is in 
the germ plasm that produces white eyes, it also produces these 
other modifications as well and modifies not only such ‘super- 
ficial’ things as color, but also such ‘fundamental’ things as 
productivity and viability.” A gene in one chromosome may 
influence or inhibit the genes located in other chromosomes and 
change in many ways the characteristics or constitution of the 
mutant. But even in the origin of heterogametic forms should 
the soma of the individual producing the microgametes (the 
male) remain similar in form to the macrogamete producer 
(the female), as it does in many marine forms, including even 
annelids and echinoderms, still there would remain that genetic 
difference in all the cells of the individual, and any future muta- 
tion would arise either in the presence or the absence of the 
gene affecting the fundamental difference between the sexes. 
