12 Alfred Russel Wallace, LL. D. 



that it is now the creed of a scientific school of the country- 

 men of Darwin and Wallace, and it has influenced the 

 thought of English-speaking people everywhere. That 

 natural selection is not the primary but a secondary factor 

 in evolution it has been my aim to show in various pub- 

 lications since 1868, and an active school of evolutionists 

 in America, England, and Germany occupies this position. 

 In Germany, Nageli and Eimer ; in England, Spencer, 

 Henslow, Turner, and Geddes ; and in America, Hyatt, 

 Jackson, Packard, Osborn, Kyder, Sharp, and Ball, have 

 made important contributions to this doctrine ; and as, in 

 the case of most of these writers, their doctrine includes 

 the essential of the position of Lamarck, the term Neo- 

 lamarckian is appropriate to this school and to its opinions. 

 To the opposite school the term Neodarwinian or Postdar- 

 winian has been applied. 



The failure of the Neodarwinian school to enter into a 

 consideration of the origin of variation has precluded them 

 from researches into the mechanical causes of modifications 

 of structure, whether proceeding from the movements of 

 the organism in relation to its environment, or whether due 

 to the action of the environment on the organism. Yet 

 they have occasionally slipped into Lamarckian explana- 

 tions of the structures and colors of animals. Lankester 

 has admitted that the spiral coil of the gastropod mollusca 

 was due to an unsymmetrical position of the shell of the 

 animal during growth. Wallace has suggested that the ro- 

 tation of the eye of the flat-fish from one side of the head to 

 the other was due to the effort of the animal to direct that 

 eye upward, as the body gradually acquired the habit of lying 

 and swimming on one side. Poulton ascribes the imitative 

 colors of the pupae of certain butterflies to the effect of the 

 colors of the environment on the nervous organism of the 

 caterpillar when about to change. But these explanations 

 have been abandoned by Lankester and Wallace as implying 

 the insufficiency of the action of natural selection to pro- 

 duce the observed results. 



The opinions of Weissmann lend support to the Neodar- 

 winians. This author declares that acquired characters can 

 not be inherited, so that if use and disuse should produce 

 modifications in the structure of adult animals, they could 

 not be transmitted to their descendants. If this be true, 

 the Lamarckian position is founded on error. This doc- 

 trine is accepted by Wallace in his last work (Darwinism). 



