368 PROCEEDINGS OF THE AMERICAN ACADEMY. 



tion a combination of the factors suggested by the Buflfbn and Geof- 

 froy St. Hilaire school, which insisted on the direct action of the 

 milieu, and of Lamarck, who relied on the indirect action of the en- 

 vironment, adding the important factors of need and of change of 

 habits resulting either in the atrophy or in the development of organs 

 by disuse or use, with the addition of the hereditary transmission of 

 characters acquired in the lifetime of the individual. 



Lamarck's views, owing to the early date of his work, which was 

 published in 1809, before the foundation of the scieuces of embry- 

 ology, cytology, palaeontology, zoogeography, and in short ail that 

 distinguishes modern biology, were necessarily somewhat crude, though 

 the fundamental factors he suggested are those still invoked by all 

 thinkers of Lamarckiau tendencies. 



Keolamarckism gathers up and makes use of the factors both of the 

 St. Hilaire and Lamarckian schools, as containing the more funda- 

 mental causes of variation, and adds those of geographical isolation 

 or segregation (Wagner and Gulick), the effects of gravity, the 

 effects of currents of air and of water, of fixed or sedentary as opposed 

 to active modes of life, the results of strains aud impacts (Ryder, 

 Cope, and Osborn), the principle of change of function as inducing 



some cases rapid evolution may occur. The present writer, contrary to pure 

 Darwinians, believes that many species, but more especially types of genera 

 and families, have been produced by changes in the environment acting often 

 with more or less rapidity on the organism, resulting at times in a new genus, 

 or even a family type. Natural selection, acting through thousands, and some- 

 times millions, of generations of animals and plants, often operates too slowly ; 

 there are gaps which have been, so to speak, intentionally left by Nature. 

 Moreover, natural selection was, as used by some writers, more an idea than 

 a vera causa. Natural selection also begins with the assumption of a tendency 

 to variation, and presupposes a world already tenanted by vast numbers of 

 animals, among which a struggle for existence was going on, and the few were 

 victorious over the many. But the entire inadequacy of Darwinism to account 

 for the primitive origin of life forms, for the original diversity in the dif- 

 ferent branches of the tree of life forms, the interdependence of the creation of 

 ancient faunas and floras on geological revolutions, and consequent sudden 

 changes in the environment of organisms, lias convinced us that Darwinism 

 is but one of a number of factors of a true evolution theory ; that it comes in 

 play only as the last term of a series of evolutionary agencies or causes ; and 

 that it rather accounts, as first suggested by the Duke of Argyll, for the pres- 

 ervation of forms than for their origination. We may, in fact, compare Dar- 

 winism to the apex of a pyramid, the larger mass of the pyramid representing 

 the complex of theories necessary to account for the world of life as it has 

 been and now is. In other words, we bel'eve in a modified and greatly extended 

 Lamarckianism, or what may be called Neo-Lamarckianism." 



