174 LIFE AND HABIT. 



but we should also expect that a cross should have a 

 tendency to introduce a disturbing element, if it be too 

 wide, inasmuch as the offspring would be pulled hither 

 and thither by two conflicting memories or advices, much 

 as though a number of people speaking at once were 

 without previous warning to advise an unhappy per- 

 former to vary his ordinary performance one set of 

 people telling him he has always hitherto done thus, 

 and the other saying no less loudly that he did it thus ; 

 and he were suddenly to become convinced that they 

 each spoke the truth. In such a case he will either 

 completely break down, if the advice be too conflict- 

 ing, or if it be less conflicting, he may yet be so 

 exhausted by the one supreme effort of fusing these 

 experiences that he will never be able to perform 

 again; or if the conflict of experience be not great 

 enough to produce such a permanent effect as this, 

 it will yet, if it be at all serious, probably damage 

 his performances on their next several occasions, 

 through his inability to fuse the experiences into 

 a harmonious whole, or, in other words, to understand 

 the ideas which are prescribed to him; for to fuse is 

 only to understand. 



And this is absolutely what we find in fact. Mr. 

 Darwin writes concerning hybrids and first crosses: 

 " The male element may reach the female element, 

 but be incapable of causing an embryo to be developed, 

 as seems to have been the case with some of Thuret's 

 experiments on Fuci. No explanation can be given 

 of these facts any more than why certain trees cannot 

 be grafted on others." 



