INHERITANCE OF ACQUIRED CHARACTERS 95 



the inheritance of acquired characters, however ingenious 

 or plausible, is not tantamount to the proof that such in- 

 heritance occurs de facto. This is the very point at issue, 

 which has to be proved. 



Galton was the first of the modern biologists who threw 

 doubt on the evidence adduced in favour of this contention, 

 and he shaped his theory of heredity in accordance with his 

 conviction, as we have demonstrated in a previous chapter. 

 But it is first and foremost Weismann who, led by theo- 

 retical considerations, came to an utter disbelief in the 

 long-accepted notion that acquired characters are inherited. 

 He has ever since been the champion of the opposite school 

 of biology, which, disregarding altogether the effect of 

 acquired characters for the evolution of species, finds the 

 explanation of organic changes exclusively in Natural 

 Selection and other collateral agencies. 



1 1. —THE FACTS AND THEIR INTERPRETATION. 



Before entering into the full discussion of the question, it 

 will be wise first to clear the issue by defining what are 

 acquired characters. This is the more necessary as a good 

 deal of confusion and useless discussion has arisen from 

 authors applying to the term different meanings. First of 

 all, we must point out that " acquired " in the biological 

 sense is not synonymous with " new." A character may be 

 new for an individual or the race, and yet not be acquired. 

 Thus, the beard in a man is new for each separate individual, 

 but we know that it is part of the male inheritance, and 

 not newly acquired. Or by the union of two different 

 germs a new character may appear, as in hybrids, j^et such 

 a character, though new for the race, is not acquired. By 

 " acquired " characters, in the technical sense of the word, 

 we understand " modifications of the body due to environ- 

 mental or functional changes, and not inherent in the 

 germ." They are what Weismann has called " somatic 

 modifications, in contradistinction to germinal variations," 



