THE THEORY OF DESCENT 277 



to belong to the acquired group of organic specifications ; 

 their inheritance, as will be seen later on, would hardly be 

 quite a pure instance of what we are searching for. In no 

 case can true variations claim to be of great importance in 

 problems of transformism. 



But what is known about the inheritance of those 

 properties which beyond any doubt may be said to have 

 originated in the adult individual as such, and of which 

 lesions and adaptations proper, as shown for instance among 

 amphibious plants, are instances of the two most typical 

 groups ? l Weismann did good service by putting an end 

 to the scientific credulity which prevailed with regard to 

 this subject. "Weismann was led by his theory of the germ 

 plasm to deny the inheritance of acquired characters of the 

 typical kinds. He could not imagine how the effect of any 

 agent upon the adult, be it of the merely passive or of the 

 adaptive kind, could have such an influence upon the germ 

 as to force it to produce the same effect in spite of the 

 absence of that agent. In fact, that is what the inheritance 

 of acquired characters would render necessary, and a very 

 strange phenomenon it would be, no doubt. But, of course, 

 taken alone, it could never be a decisive argument against 

 such inheritance. I fully agree, that science is obliged to 

 explain new facts by what is known already, as long as it is 

 possible ; but if it is no longer possible, the theory of course 

 has to be changed, and not the facts. On this principle one 

 would not neglect the fact of an inheritance of acquired 

 properties, but on the contrary one perhaps might use it 

 as a new evidence of vitalism. 



1 Certain English authors have applied the term "modification" to all kinds 

 of organic properties acquired from without, whether they are adapted or not. 



