356 BIOLOGY 



universal acceptance. With the acceptance of Weismann's 

 theory, it was no longer possible to look upon acquired 

 characters as transmitted to posterity. As a result, the 

 Lamarckian factors were of necessity thrown overboard, since 

 they all involved the inheritance of acquired characters. It was 

 no longer possible to believe that the direct effect of the environ- 

 ment upon the individual, or the effect of the disuse of organs, 

 could have any influence upon posterity; and as rapidly as 

 Weismann's theory of heredity received acceptance the so-called 

 Lamarckian factors were discarded, until to-day they are not 

 generally regarded as factors in producing race variation. The 

 adherents of Weismann have thought that the only possible 

 factor left to produce evolution was the natural selection of the 

 congenital variation. Congenital variations, since they are due 

 to variations in the germ plasm, will be transmitted; and the 

 natural selection of these congenital variations will remain as 

 the great factor in the development of type. Indeed, the fol- 

 lowers of Weismann took this extreme view and held, and still 

 hold, that the only factor which has produced race evolution 

 has been the natural selection of those characters which start 

 as variations in the germ substance. But the dispute between 

 the followers of Lamarck's older views and Weismann's new 

 views has never yet been positively settled. Some naturalists 

 accept Weismann's views in toto; others have not regarded them 

 as sufficiently well demonstrated; while quite a number of prom- 

 inent biologists, including Spencer, Packard, Cope, and others, 

 have held to a modern form of Lamarck's views, believing that 

 in some way, and under some circumstances, acquired characters 

 might have influence upon the offspring and therefore might 

 direct the line of race divergence. The question has not been 

 definitely settled; but at the present time the balance of evidence 

 seems to be against believing that acquired characters are trans- 

 mitted, and therefore against the retention of any of the so-called 

 Lamarckian factors, that are based upon the direct action of the 

 environment upon the individual. 



