THE ADVANCE OF SCIENCE 129 



agencies shows new responsive quantities in those parts 

 of its structure concerned, new or acquired characters. 



* So far, so good. What Lamarck next asks us to 

 accept, as his " second law," seems not only to lack the 

 support of experimental proof, but to be inconsistent with 

 what has just preceded it. The new character which is 

 ex hypothesi, as was the old character (length, breadth, 

 weight of a part) which it has replaced a response to 

 environment, a particular moulding or manipulation by 

 incident forces of the potential congenital quality of 

 the race is, according to Lamarck, all of a sudden 

 raised to extraordinary powers. The new or freshly 

 acquired character is declared by Lamarck and his 

 adherents to be capable of transmission by generation ; 

 that is to say, it alters the potential character of the 

 species. It is no longer a merely responsive or reactive 

 character, determined quantitatively by quantitative 

 conditions of the environment, but becomes fixed and 

 incorporated in the potential of the race, so as to persist 

 when other quantitative external conditions are substi- 

 tuted for those which originally determined it. In 

 opposition to Lamarck, one must urge, in the first place, 

 that this thing has never been shown experimentally to 

 occur ; and in the second place, that there is no ground 

 for holding its occurrence to be probable, but, on the 

 contrary, strong reason for holding it to be improbable. 

 Since the old character (length, breadth, weight) had not 

 become fixed and congenital after many thousands of 

 successive generations of individuals had developed it in 

 response to environment, but gave place to a new 

 character when new conditions operated on an individual 

 (Lamarck's first law), why should we suppose that the 

 new character is likely to become fixed after a much 

 shorter time of responsive existence, or to escape the 



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