LAMARCKISM 427 



choose a male whose beauty, grace or other conspicuous 

 feature satisfies her esthetic sense. The survival of the 

 fittest is thus determined by the female. As a matter 

 of fact it has been shown that among many insects the 

 wings may be dyed or even cut off without disturbing the 

 mating instinct. The sexes are attracted by special odors, 

 and not by color. Certain crabs, and related species, as 

 well as the spiders, mate by means of the sense of touch. 

 Among the birds the female usually pays no attention 

 to the male who is " showing off." The remarkable bird- 

 dances undergone by certain* species occur after mating 

 has already taken place. From these and many other 

 examples, which can be cited, there is little evidence that 

 the female chooses her mate. On the other hand it is 

 not clear that such structures as the great tail of the 

 peacock, the tuft of hair-like feathers on the breast of the 

 turkey, the wattles, plumes, spines, knobs, and conspicu- 

 ous colors possessed by the males of many species are of 

 supreme importance in the life and death struggle for 

 existence. In short, there is as yet no satisfactory all- 

 embracing explanation of the significance of secondary 

 sexual characters. 



Lamarckism. — It is an uncontested fact that animals 

 and plants are continually being molded under the in- 

 fluence of their surroundings. Food and climate are im- 

 portant agents in this respect. Exercise increases the size 

 of muscles and disuse causes their shrinkage. Drugs, such 

 as morphine and alcohol, modify the organism, and many 

 other forces cause more or less extensive alterations. 

 According to the French scientist, Lamarck (1744-1829) 

 the characters or modifications thus acquired by the 

 organism during its lifetime are supposed to be inherited 

 by the offspring. This simple plausible theory was ac- 

 cepted by Darwin as a factor in evolutionary processes, 

 and was likewise accepted as a matter of course by scien- 

 tists and laity alike until recent years. 



The long neck of the giraffe, according to the Lamarck- 



