96 PETER OKKELBERG 



('05) in the case of Protozoa. A normally functioning cell is 

 regarded by him as a hermaphrodite which has the male and 

 female qualities equally balanced. The differentiation which 

 leads to the formation of gametes is due to inequalities of cell 

 division which result in a more or less imperfect distribution of 

 the qualities of the parent cell between the daughter cells, so 

 that some cells may receive more male and others more female 

 properties. The male cells show greater kinetic energy; the 

 female cells greater trophic energy. The opposite tendencies 

 accumulate in different cells which thus become one-sided in their 

 vital activities. The want of balance may reach a stage in which 

 syngamy must take place or the cell dies. 



A similar idea was advanced above, in my discussion of the 

 appearance of two kinds of germ cells in the sex glands of the 

 lamprey. In this case, too, the development of the two kinds 

 of cells in the same gland may be due to a disturbance in the 

 metabolism of the cell during mitosis, which results in the develop- 

 ment of a cell along either one or the other of two potential lines. 

 It is conceivable also that there may be various grades of male 

 and female potentiahties in the germ cells thus formed, and that 

 even in their mature condition some cells may be more strongly 

 sexed than others. After fertilization, the same differences of 

 sex potentialities may exist, and, in so far as no other factors are 

 introduced to disturb the relative sex potentiahties, the sex of 

 the resultant animal may be said to be determined at the time of 

 fertilization. 



Whether or not these differences in sex potentiahty are the 

 result of a variation in the chromosomal make-up of the cells is 

 not certain. This suggestion appears contrary to certain known 

 facts of sex-linked inheritance, which seem to require for their 

 interpretation that the sex characters reside in the same chromo- 

 some as the sex-linked character. It might be assumed equally 

 well, however, that certain characters appear, only when asso- 

 ciated with a certain kind of cell metabolism which may be pecu- 

 liar to one or the other sex. This conception might also account 

 for the exceptions to the inheritance of sex-linked characters 

 which are difficult to explain by the chromosomal theory. 



