448 SCIENCE PROGRESS 



of one sex are latent in the opposite one. It is extremely 

 important that this phrase "latent" should not be miscon- 

 strued. The manner in which the Mendelians picture this 

 " latency " is to suppose that the members of both sexes are 

 heterozygotes, half of whose germ-cells contain the male 

 character and half the female character. They do not believe — 

 and this is the essence of the Mendelian doctrine of gametic 

 purity — that the germ-cell which produces a female contains 

 maleness as well Maleness would only be admitted to be 

 latent in a woman in the sense that greenness is latent in a 

 cross between a green and a yellow pea. 



There is another sense in which the phrase latent is used 

 which must not be misconstrued. When a grey-skinned was 

 crossed with a white-skinned pea, the hybrids, which were 

 grey with purple spots, gave in F2 nine greys with purple 

 spots, three greys, and four whites, three of which, it will be 

 remembered, were whites carrying purple spots, which was 

 not manifested because the grey was absent. Bateson protests 

 against the statement that purple spot is latent in these whites. 

 " Sulphate of copper," he says, " is blue and chloride of copper 

 is green, but it would be improper to speak of blue as latent in 

 sulphuric acid, or of green as latent in hydrochloric acid." 



