182 EVpfrTION AND ANIMAL LIFE 



tact, etc. At least, there is not recorded any satisfactory 

 proof of the inheritance of these acquired characters, and there 

 is definite proof that many of them are not inherited. And 

 most biologists, as helpful in many ways to a clearing up of 

 the problem of adaptation and species-forming as the actu- 

 ality of such inheritance would be, believe themselves un- 

 able to accept this fact, in the light of our present knowl- 

 edge. (This matter of the inheritance of acquired characters 

 is discussed in Chapter XI. The assumption of this inheritance 

 is a fundamental part of the Lamarckian explanation of evo- 

 lution.) 



Second, certain characters peculiar to sex are inherited only 

 according to sex and not by all the young. These characters 

 include not only the differing reproductive organs themselves, 

 but those many, various, and often most remarkably developed 

 so-called secondary sexual characters, such as the tufts and 

 plumes and brilliant plumage of male birds, the antlers of male 

 deer, the specialized antennae, skeletal processes, and color pat- 

 t cms of many male insects, and the reduced wings of many female 

 insects, etc., etc. Even in cases of parthenogenetic reproduc- 

 tion (i.e., reproduction in which the male takes no part), sex and 

 the sex characters of the offspring have no direct relation to the 

 sex and sex characters of the mother. The queen honey bee 

 produces, in fact, exclusively drones (male bees) when she lays 

 unfertilized eggs, while on the contrary the parthenogenetic 

 offspring of the Aphids (plant lice) are all females for several 

 generations, and then in a single generation both males and 

 females. 



Finally, certain parental characters, even though blast ogenic, 

 may not appear in the offspring, but be inherited by them in 

 latent condition, to appear in their young or perhaps even in a 

 later generation. It is obvious, too, that where a certain char- 

 acter in the mother is represented in the father by one of oppo- 

 site condition, as where the mother is very short, the father very 

 tall, the mother a brunette, the father light-haired, a given child 

 can inherit the character in only one condition. That is, in all 

 cases of biparental reproduction, and they compose the majority 

 of cases in both animal and plant kingdoms, the inherited char- 

 acters cannot be all those possessed by both parents, but must 

 be either those of one or the other, or a mosaic of them, or a 

 blend or fusion of them. And this introduces us to that phase 



