414 The Living Plant 



have more powerful arms than would have been the case had 

 their father adopted some less strenuous trade. Most of our 

 popular beliefs tend to the same end, especially as to moral and 

 intellectual qualities; for it is commonly supposed that the finer 

 mind developed in an individual by high education, or the de- 

 generacy produced by submission to vice, are somehow trans- 

 mitted to the offspring. If a feature is hereditary for one genera- 

 tion, however, it is hereditary for more; and thus, according to 

 Lamarck, a character can go on piling up generation after genera- 

 tion until it reaches a degree of development sufficient, along with 

 associated changes, to make its possessor rank as a new species. 

 Of course, on this principle, all individuals born into the world 

 have an equal chance for survival, and mere chance would de- 

 termine success. This method of evolution is illustrated in com- 

 parison with that by natural selection on the accompanying 

 diagram (figure 172). 



The Lamarckian explanation of evolution has a great merit in 

 its simplicity, but has the fatal defect that the crucial trans- 

 mission of acquired characters is not confirmed either by ordinary 

 observation, or by any experiment which has been devised to 

 test it. Moreover, that gigantic system of experiment always in 

 progress in plant and animal improvement by man has failed to 

 yield one fact in its support. Furthermore, the phenomena 

 which apparently are the strongest in its favor can be explained 

 more simply in other ways. Thus, the blacksmith's sons, it is 

 true, tend to have stronger arms than ordinary men; but this 

 need not mean that they inherited the stronger arm acquired by 

 the father, but only that they inherited the same robust proto- 

 plasm which enabled the father to become a successful smith. So 

 the children of highly educated parents are apt to be bright, not 

 because they inherited the educated minds of the parents, but 

 because they inherited the finer quality of mind-protoplasm 

 which made high education in the parents a possibility; and so 

 with the children of tuberculous parents, who inherit not the 



