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SCIENCE 



[N. S. Vol. XLIII. No. 1108 



statements as to our attitude toward the 

 work and our fellow workers. 



For this purpose let us give our atten- 

 tion to some of the more important swings 

 of our pendulimi that have taken place 

 since the appearance of that epochal event, 

 the appearance of Darwin's "Origin of 

 Species by Means of Natural Selection." 



As is usually the case, the workers im- 

 mediately following Darwin were inclined 

 to outdo their leader, to out-Darwin Dar- 

 win and to overwork the theory which he 

 advanced, making natural selection the 

 sole efficient cause of the origin of species. 



By far the ablest and most prominent 

 writer who thus swTing the pendulum 

 away from the sane and reasonable path 

 along which Darwin had advanced was 

 August Weismann, who startled the world 

 with his declaration that acquired charac- 

 ters were not inherited, and advanced the 

 theory of the continuity and stability of 

 the germplasm. This fascinating and mi- 

 nutely worked out scheme for advancing 

 and clenching the argument for natural 

 selection found many opponents and manj' 

 ardent advocates. The battle was raged 

 round the chromosomes as the center, and 

 their intricacy and theoretical details were 

 elaborated by Weismann and others until 

 germplasm and somatoplasm, determinants, 

 ids and idents were the stock in trade of 

 every callow as well as learned biologist, 

 in spite of the fact that these latter were 

 unknown and unknowable. Indeed the 

 whole fabric bid fair to break down by the 

 very complexity of the concepts borne of an 

 endeavor to imagine a machinery adequate 

 to account for the increasingly intricate re- 

 quirements of the known facts of heredity 

 and evolution. 



At the present time these terms have been 

 in part abandoned and in part supplanted 

 by others, but the pendulum had not only 

 swung far to one side, but had actually ad- 



vanced. This advance is probably best 

 shown in the almost universal acquiescence 

 at present in the idea that acquired charac- 

 ters are, at best, seldom inherited and that 

 such cases are too few to be seriously con- 

 sidered as affecting greatly the trend of 

 evolution. 



But another, and perhaps more impor- 

 tant gain was in the impetus given to the 

 study of cytology, particularly the be- 

 havior of the nucleus, and the consequent 

 marvelous improvement in the technique of 

 the study of the chromosomes and the fas^ 

 cinating phenomena of fertilization and 

 cell division. These are indeed important 

 gains, however much the details of the 

 Weismannian doctrine may be modified by 

 subsequent discoveries. 



But suddenly the pendulum began to 

 swing the other way. Theodore Eimer in 

 Germany vigorously, if somewhat un- 

 wisely, attacked the position of Weismann, 

 being followed by others in Europe and by 

 many of our own countrymen led by our 

 famous paleontologist, Professor E. D. 

 Cope. These latter formed what was then 

 known as the "American School" of Neo- 

 Lamarckians, who believed that acquired 

 characters were inherited and that varia- 

 tions appear in definite directions and 

 "are caused by the interaction of the or- 

 ganic being and its environment." 



Few of the younger naturalists present 

 can have any conception of the heat of the 

 battle waged between the Neo-Darwinian 

 and Neo-Lamarckian schools in the last de- 

 cade of the nineteenth century. Professor 

 Cope himself was a born controversialist 

 and one of the most trenchant and quick- 

 witted debaters among American biolo- 

 gists. Many of the older zoologists will 

 picture to themselves his alert pose, his 

 square-cut chin and the light of battle in 

 his eye as he debated the question in meet- 

 ings of this association; and discussed cat- 



