HEREDITY. THEORY OF WEISMANN. 269 



If we can find out the reason why a child is like 

 its parents, we shall doubtless know why he is dif- 

 ferent in certain respects. Scientists are searching 

 to-day after some explanation of heredity. Already 

 several hypotheses have been advanced ; but it will 

 be admitted that they are only hypotheses, more or 

 less probable, but usually created to fit the facts, 

 instead of being called for by them. None of them 

 are far enough advanced to be rightly called theo- 

 ries, and it would as yet be impossible to find any 

 two scientists who agree upon any positive conclu- 

 sion on this matter. Of the various hypotheses, 

 probably not one is fully accepted by any person but 

 its author. These theories are, however, a neces- 

 sary part of the explanation offered for evolution, 

 and it is desirable before closing this account of the 

 theories of evolution to consider at least two of 

 them which bear particularly upon the subject 

 we are considering. 



Heredity. Theory of Weismann. 



In looking at this question of heredity, we find, 

 to start with, that not only are the explanations of 

 the law in dispute, but even the facts are by no 

 means agreed upon. That an animal can inherit 

 from its parents, is everywhere admitted j. but be- 

 yond this very general statement there is little 

 unanimity of opinion. Whether it can inherit all 

 sorts of peculiarities, or only certain definite kinds ; 

 whether it inherits from both parents alike, or from 

 only one ; or whether one sort of traits is inherited 

 from the male parent, and another from the female 



