THE STUDY OF HEREDITY 325 



party, nor do I see that the facts contradict each other in any 

 way. The mode of transmission of characters from individual to 

 individual is quite a different matter from that of recording the 

 average standard of any given character in successive generations 

 of a large number of individuals. 



Where the real difficulty to the outsider interested in heredity 

 comes in is that the Mendelians treat all characters as unit 

 characters which do not blend at all in the offspring. A father 

 with a certain definite character has offspring by a mother who 

 has the opposite (the allelomorph) of this character, including in 

 opposite the presence or absence of a character. The immediate 

 offspring will show one or the other of this pair of characters ; 

 in the next generation individuals will appear in which one or 

 the other character will be produced to the exclusion of the 

 opposite, and in these the characters extracted from the cross 

 will behave more or less as pure characters and breed true. 

 This is Mendelian or alternative inheritance. Prof. Davenport 

 in his very valuable book practically ignores any other kind of 

 inheritance, the result being that the uninformed reader must 

 believe that all characters are inherited in this alternative 

 manner. This is strange, as he wrote in 1906 : " Very frequently 

 if not always the character that has once been crossed has been 

 affected by its opposite with which it was mated and whose 

 place it has taken in the hybrid. It may be extracted therefrom 

 to use in a new combination, but it will be found altered. This 

 we have seen to be true for almost every character sufficiently 

 studied. . . . Everywhere unit characters are changed by 

 hybridism." 1 There is, of course, not the slightest doubt that 

 many characters present in the parent appear in succeeding 

 generations of offspring in an alternative manner, but is this true 

 of all characters ? And if it be not, is there anything which 

 suggests which characters are transmitted in this way ? Prof. 

 J. A. Thomson gives but little help in this direction. In an 

 admirable account of the Mendelian theory and experiments, he 

 appears to agree with its most bigoted supporters. He gives 

 also an admirable account of the theories and observations 

 which are supposed by some to contradict the Mendelians, and 

 he appears to agree with those who uphold them. 



Now it is quite obvious that the bulk of the characters in any 

 individual are not inherited in an alternative manner. Whether 



1 Inheritance in Poultry ', p. 80. 



