450 Thos. H . Montgomery, Jr. 



extending from such with the greatest to such with the least repro- 

 ductive abihty; the former would be incipient females, the latter, 

 incipient males. With this difference in reproductive ability 

 would certainly be associated metabolic differences, indeed the 

 latter would probably occasion the former. 



Even racially older than observable sex difference is the process 

 of conjugation, which at the start had no immediate connection 

 with reproduction. Conjugation has been fixed by selection in 

 that it aids the race by strengthening the reproductive individuals 

 and making them more efficient in generation, conjugation being 

 in certain Protozoa a form of nourishment. 



Conjugation being then of use to the race by strengthening or 

 stimulating the reproductive individuals, selection would preserve 

 those segregations of individuals in which variation with regard 

 to reproductive ability is most marked, for in such species con- 

 jugation would be most effective by occasioning the most diverse 

 substance intermixture. Selection coupled with segregation 

 would in time tend to eliminate the means, as the least useful in 

 conjugation, and to preserve those individuals most dissimilar in 

 reproductive capacity. This would terminate in a group of repro- 

 ductive individuals, females, and of fertilizing individuals, males, 

 not connected by intermediates. 



With regard to the sex ratio of a particular species. Pike {I.e.) 

 concludes that it may "be looked upon as one of the physiological 

 adaptations of the species, determined by the conditions of its 

 existence. * h« * jjp gg^ is hereditary, we might reasonably expect 

 that the relative numbers of male and female births in any species 

 would be those which, after deducting the early deaths, would 

 confer upon the species at the period of sexual maturity of its 

 individuals the greatest advantage in the struggle for existence 

 so far as the production of young is concerned. " This explanation 

 is to my mind entirely just, and the factors would be, to carry the 

 idea out further than Pike did, those of selection and segregation. 

 Those species continue that survive in the struggle for life, and 

 this struggle is the endeavor to insure offspring. Selection oper- 

 ates by removing those species whose reproductive ability can- 

 not successfully meet this struggle. Therefore selection would 



