REVERSION TO THE WILD FORM. 209 



unequal (compare p. 17). All such relapses are to be 

 brought under the law of interrupted or latent transmission, 

 although the number of intervening generations may be 

 enormous. 



When cultivated plants or domestic animals become wild, 

 when they are withdrawn from the conditions of cultivated 

 life, they experience changes which appear not only as 

 adaptations to their new mode of life, but partially also as 

 relapses into the ancient original form out of which the cul- 

 tivated forms have been developed. Thus the different 

 kinds of cabbage, which are exceedingly different in form, 

 may be led back to the original form, by allowing them to 

 grow wild. In like manner, dogs, horses, heifers, etc., when 

 growing wild, often revert more or less to a long extinct 

 generation. An immensely long succession of generations 

 may pass away before this power of latent transmission be- 

 comes extinguished. 



A third law of conservative transmission may be called 

 the law of sexual transmission, according to which each sex 

 transmits to the descendants of the same sex peculiarities 

 which are not inherited by the descendants of the other sex. 

 The so-called secondary sexual characters, which in many 

 respects are of extraordinary interest, everywhere furnish 

 numerous examples of this law. Subordinate or secondary 

 sexual characters are those peculiarities of one of the two 

 sexes which are not directly connected with the sexual 

 organs themselves ; such characters, which exclusively belong 

 to the male sex, are, for example, the antlers of the stag, the 

 mane of the lion, and the spur of the cock. The human 

 beard, an ornament commonly denied to the female sex, be- 

 longs to the same class. Similar characteristics by which 



