GENETICS 



ondary sexual characters, and also that the determin- 

 ers for the opposite sex are often present in a latent 

 condition, or, in other words, that the organism, 

 either male or female, is heterozygous until respect to 

 sex. 



If a female of the annelid worm Ophiotrocha, for 

 example, is cut in half, it is effectually castrated, be- 



Male 



Parasitical^ castrated mate 



Female 



FIG. 64. The crab, Inachus, parasitized by the cirripede, SacculiT 

 Evidence that a Mendelian sex determiner is correlated with 

 ondary sexual characters " and that the male is heterozygous for 

 while the female is homozygous. After Smith. 



cause the ovaries are in the posterior part of the 

 It has the power of regeneration, however, but wh( 

 a new posterior part is formed, it contains, not femah 

 but male reproductive organs. The worm is, th( 

 fore, now a male, as shown by the presence of test( 

 instead of ovaries, proving that it was originally 

 heterozygous with respect to sex. carrying one 

 latent. 



