SEX INHERITANCE 133 



of chromosomes; in some races the male has one 

 less chromosome than the female, in other races 

 the female has one less than the male. There are 

 races in which the male has the haploid (full) 

 number of chromosomes, while the female has the 

 double number. The gametes giving rise to these 

 two kinds of individuals are sometimes loosely re- 

 ferred to as male and female, but they are properly 

 only male-producing and female-producing in certain 

 combinations; for, as shown in non-disjunction, the 

 same gametes if they form other combinations may 

 give a result that is just the opposite from that 

 which usually occurs. Thus, a "female-producing" 

 X-sperm will give rise to a male if it enters an egg 

 without an X. 



The same terms male and female have been 

 carried over to the protozoa — organisms that are 

 one-celled like the gametes of multicellular forms; 

 but obviously the words are here used in a different 

 sense. In what manner the protozoa are to be 

 compared with tlie liigher forms remains uncertain 

 until we have more definite information concerning 

 the chromatin changes that take place before, 

 during, and after, conjugation. 



In the mosses and liverworts an interesting 

 situation exists. There are two alternating gener- 

 ations, one is (iii)l()id (sporophyte), the other haploid 

 (gametophyte). In mosses and liverworts with 

 separate sexes the sexual generation is haploid. 



Allen has found in one of the liverworts, Sphicro- 

 carpus, that there is an unequal pair of chromosomes 



