SEXUALITY 681 



3, 2, and 1, respectively; and the sexes L, M, N, and O were said to be 

 — in sex, with valences of 1, 2, 3, and 4 respectively. In this group, 

 Moewus (1937b, 1938a) later held that the sex previously called -f was 

 female, the one called — male. These designations, together with other 

 pertinent information on the strength of sex reaction and sex stuffs, are 

 shown in Table 10. (Identification of male and female in the first group 

 of races has not yet been reported. ) 



The remainder of the interpretation is largely genetic and will be dis- 

 cussed here only insofar as appears necessary for a satisfactory under- 

 standing of the general phenomena of sexuality and their relation to 

 the theory of Hartmann. For further details the reader should consult 

 Chapter XV, "Inheritance in Protozoa," by H. S. Jennings. Moewus 

 gives evidence for two series of multiple alleles affecting sex in the 

 hraumi, dresdensis, paupera, eugametos group of species: at one locus 

 is a series of genes Ml, M2, M3, and M4, determining the four valences 

 of male gametes; at another linked locus is a series of genes Fl, F2, F3, 

 and F4, determining the corresponding four valences of female gametes. 

 When crossing over takes place between these two loci, nuclei with a 

 chromosome lacking both an M and F gene die, while those with both 

 M and F genes survive. In the latter, if the valences are equal, sex is 

 determined by nongenetic factors, the valence is unchanged, and both 

 male and female gametes arise within a single clone; but if the valences 

 are unequal, sex is determined by the gene of stronger valence and the 

 resulting valence is the arithmetic difference between the valences of the 

 two genes. In races such as C. eugametos f. subheteroica, in which each 

 clone is always prevailing of one sex, another pair of genes determines 

 which sex shall prevail. The genetic relations have not been worked out 

 so fully in the paradoxa-pseudoparadoxa group of races, but there also 

 multiple alleles are held to operate. Although evidence as to whether 

 the -\- and the — genes are alleles has not been reported, observations 

 on regular non-disjunction showed that the sex and valence resulting 

 from the presence of two or more alleles was their algebraic sum. 



The various genes affecting sex are considered to be the sex realisators, 

 in agreement with Hartmann. They are held to operate by acting on the 

 underlying sexual Anlagen, or potencies, A and G, the genes of dif- 

 fering valence acting on A and G to different extents. Sexual union then 

 results when gametes differ in sex or in sex valence by as much as 2. 



