SEXUALITY 705 



work of Moewus ( 1939a) on Chlamydomonas shows how what appears, 

 through biological analysis, to be a multiple sex system may be reduced, 

 through chemical analysis, to a fundamentally dual system. Further in- 

 vestigation is, of course, required to ascertain whether the multiple sex 

 systems in ciliates are, in fact, similar in this respect to the system in 

 Chlamydo m onas. 



A number of the interpretations of sex relations in ciliates employ 

 the concepts male and female, as set forth above. Many authors follow 

 Hartmann (1929), who holds, as has been pointed out on page 678, 

 that sex differences, wherever found, are always male and female. 

 The characters by which the female is ordinarily recognized are larger 

 size, lesser activity, greater storage of nutritive reserves, and egg-like 

 form; and the male by the corresponding opposed characters. In attempt- 

 ing to apply these views, however, numerous difficulties are encountered. 

 In the Vorticellidae, both gamete nuclei in the microconjugant are held 

 to be male; yet only one of them shows the "male" character of activity 

 by migrating into the macroconjugant. In Opisthotrichum, the migratory 

 gamete nucleus has the form of a sperm, but it has the "female" char- 

 acter of much greater size than the stationary gamete nucleus. The diffi- 

 culty of using size as an index of femaleness is clearly shown in the work 

 of Satina and Blakeslee (1930) on certain bread molds. In a number of 

 strains, two sexes were observed and found to be the same in all strains. 

 One sex was distinctly larger than the other in each strain, yet the larger 

 sex in one strain was shown to be identical with the small sex in others. 

 Geitler (1932) found similar difficulties in identifying the sexes in 

 diatoms by their activity. These and other difficulties have led Kniep 

 (1928), Mainx (1933), and others to abandon the concepts of male 

 and female in unicellular organisms and to view sexual union as brought 

 about by copulation-conditioning factors, some of which operate to bring 

 together the cells, others the nuclei. In the present state of knowledge, 

 this point of view appears to be preferable to one that appeals to such 

 abstract, ill-defined, and confusing concepts as fundamental maleness 

 and femaleness. 



From this point of view, the conflicts between sexual differentiation 

 in the gamete nuclei and sexual differentiation in the conjugant indi- 

 viduals present far less difficulty than from the point of view which 



