106 SEX 



characters. In simple clear-cut cases the gist 

 of the matter may be thus stated. If A be 

 a well-established, pure-bred variety with a 

 certain differentiating character (D), e. g. a 

 colour, a crest, long fur, horns ; and if B be 

 another well-established variety with a cor- 

 responding but contrasted differentiating char- 

 acter (R), e. g. another colour, no crest, short 

 fur, hornlessness ; and if A and B are crossed, 

 the hybrid offspring (Fj) will resemble one of 

 the parents only, say A, as regards the con- 

 trasted characters in question. The char- 

 acter (D) that prevails was called by Mendel 

 a dominant; the character (R) that remains 

 latent was called a recessive. (In many of 

 the cases now known the dominance is im- 

 perfect, more or less of the recessive character 

 being exhibited, but it is unnecessary to dis- 

 cuss this.) Now, if the hybrids be bred 

 together, their descendants will be of two 

 kinds, three-fourths of them with the domi- 

 nant character and one-fourth of them with 

 the recessive character. When those with the 

 recessive character are inbred, they yield 

 only recessives. They are pure or homo- 

 zygous as regards this recessive character. 

 When those with the dominant character 

 are inbred, a third of them yield only 

 dominants (to put it shortly), and two-thirds 

 of them yield dominants and recessives in the 

 previous proportion of about three to one. 

 That is to say, a third of the dominants 

 are pure or homozygous dominants; while 

 two-thirds of them are impure or heterozygous 

 in respect to the dominant character. Dia- 

 grammatically expressed, the facts are 



