DARWINISM'S PRESENT STANDING. 391 



of these acknowledged leaders of biological thought supports his 

 position upon inductive evidence. Each displays his main force 



Osborn's cham- in destructive criticism of his opponent; neither pre- 

 pionshipofthe sents his case constructively in such a manner as to 

 "unknown factors carry conviction either to his opponent or to others. In 

 of evolution." short, beneath the surface of fine controversial style 

 we discern these leaders respectively maintaining as finally estab- 

 lished theories which are less grounded upon fact than upon the 

 logical improbabilities of rival theories. Such a conclusion is deeply 

 significant; to my mind it marks a turning point in the history of 

 speculation, for certainly we shall not arrest research with any 

 evolution factor grounded upon logic rather than upon inductive 

 demonstration. A retrograde chapter in the history of science 

 would open if we should do so and should accept as established 

 laws which rest so largely upon negative reasoning. . . . 



"The first step then towards progress is the straightforward con- 

 fession of the limits of our knowledge and of our present failure 

 to base either Lamarckism or nee-Darwinism as universal princi- 

 ples upon induction. The second is the recognition that all our 

 thinking still centres around the five working hypotheses which 

 have thus far been proposed ; namely, those of Buffon, Lamarck, St. 

 Hilaire, Darwin, and Nageli. Modern criticism has highly differ- 

 entiated, but not essentially altered these hypothetical factors since 

 they were originally conceived. Darwin's 'survival of the fittest' 

 we may alone regard as absolutely demonstrated as a real factor, 

 without committing ourselves as to the 'origin of fitness.' The 

 third step is to recognise that there may be an unknown factor or 

 factors which will cause quite as great surprise as Darwin's." . . . 



"The general conclusion we reach from a survey of the whole 

 field is, that for Buffon's and Lamarck's factors we have no theory 

 of heredity, while the original Darwin factor, or neo-Darwinism, 

 offers an inadequate explanation of evolution. If acquired varia- 

 tions are transmitted, there must be, therefore, some unknown 

 principle in heredity; if they are not transmitted, there must be 

 some unknown factor in evolution." (Osborn. H. F., "The Un- 

 known Factors of Evolution," in Wood's Holl Biological Lectures, 

 pp. 79, 80, 81, 98, and 99, 1894.) 



5 Davenport, C. B., "Animal Morphology in its Relation to Other 

 Sciences," Congress of Arts and Sciences, Vol. V, pp. 244-257, 1906. 

 In this paper are pointed out in admirable manner the present- 

 moment problems, interests, and points of view of evolution biolo- 

 gists. 



6 Henry de Varigny, in "La Nature et La Vie," 1905, says that for 

 many adaptations "il n'y a pas a se dissimuler que, dans beaucoup 



