186 EEPOET— 1891. 



One of the most recent contributions to the theories of evo- 

 hition is a paper entitled "On the Origin of Sex through Cumu- 

 lative Integration, and the Relation of Sexuality to the Genesis 

 of Species," by J. A. Eyder," which has just come to hand. 



The writer regards the main end of sexuality as not being 

 merely provision for reproduction or for the occurrence of 

 variations on which natural selection may act, but regards its 

 ultimate end as being protection of the young by the develop- 

 ment of viviparity. It has become developed along two quite 

 distinct but parallel lines in the animal and in the vegetable 

 kingdoms respectively. 



To quote his own words : " The gradual development of 

 sexuality by slow stages in plants is now so well understood 

 that it is not necessary to enter into the details, which may 

 be found in any standard botanical text-book. It is sufficient 

 to indicate that the transition from asexuality to female 

 macrogouidia and male microgonidia is effected by mere 

 dilferentiation of cells as respects their size. From naked 

 oospore to carpospore is the next step, with flagellate male 

 elements. Finally, the prothallium appears first with both 

 oospheres and antherozooids ; then the prothallia themselves 

 become distinguished as small male and large female ones ; 

 then the female x^rothallium is no longer at once detached, but 

 becomes covered in, while the minor male prothallium still 

 dehisces, but finally becomes partially parasitic upon the stigma, 

 where it vegetates, and throws out a hollow process, which 

 serves to convey the new highly-modified antherozooid to the 

 ovicell. The prolonged adherence of the female prothallium to 

 the parent axis enables the next important step to be taken in 

 the evolution of the seed containing a viviparously-produced 

 embryo, provided with a store of nutriment and suitable enve- 

 lopes." 



" Similar conclusions are borne in upon the zoologist in 

 a study of the reproductive process in the animal world. From 

 asexual fragmentation, and consequent multiplication, the 

 advance to larger and smaller female and male elements was a 

 gradual one, with or without hermaphrodism. Then came 

 hermaphrodism with large female and small male germs ; then 

 maleness and femaleness as characterizing distinct individuals 

 of the same species. Finally, protective processes were deve- 

 loped." 



The "cumulative integration" of which he is constantly 

 making use is simply "assimilation beyond the needs of the 

 organism," or, in a word, overgrowth; and it is to this over- 

 growth that Eyder traces sexuality in all the phases of its 

 development. 



* Proc. Amer. Philosoph. Soc, vol. xxviii. (1890). 



