684 SEXUALITY 



Critique of the works of Moeivus on Chlamydomonas. — Attention 

 should be called to certain difficulties in some of the important features 

 of Moewus's interpretations and observations. 



1. Identification of -|- and — with female and male. Moewus's iden- 

 tification of -\- and — with female and male is based, as set forth above, 

 on two points: the two sexes in anisogamous species, especially in C. 

 coccifera, are male and female; the two sexes are the same in all races 

 and species. The point has already been emphasized that the latter is an 

 assumption, not a fact of observation. The interpretation of the two 

 sexes in C. coccifera as male and female is based on the proposition that 

 female gametes are distinguishable from male gametes by their passive 

 role in copulation, their larger size, and their nonmotility. Though these 

 criteria are widely accepted as valid, one may question whether the evi- 

 dence warrants this. The passive role of the "female" gamete in copula- 

 tion is shown by the fact that the "male" gamete empties its contents 

 into the "female" gamete. Nevertheless, the same behavior takes place 

 in a certain race of C. eugametos, in which Moewus (1933) showed 

 that it is of no sexual significance for both the -|- and the — gametes 

 may play either role in copulation. The same holds for difference in size: 

 either the -(- or the — gamete of this race of C. eugametos may be twice 

 as large as its mate. The difference in behavior is correlated with the 

 difference in size, but neither is correlated with sex. One may doubt, 

 then, whether these two criteria are of sexual significance in C. coccifera, 

 since they are clearly not significant in C. eugametos. The difference in 

 motility is perhaps stronger evidence, for only the -|- gametes of C. 

 coccifera are non-flagellated and these are generally considered to be 

 comparable to eggs. It is important to keep clearly in mind that the use 

 of the terms male and female for the gametes of all the races and species 

 of Chlamydomonas rests finally on the single fact that the -)- gametes 

 of C. coccifera lack flagella. Whether this is sufficient ground for holding 

 they are female in the same sense as the eggs of higher organisms and 

 for extending the terms male and female to the gametes in all other 

 species of Chlamydomonas that interbreed with C. coccifera must be left 

 to the judgment of the critical reader. The present author, in agreement 

 with Kniep (1928) Mainx (1933) and others, holds that such facts 

 constitute too slender a basis to justify an interpretation of such general 

 theoretical significance. 



