8o BIOLOGICAL LECTURES. 



of science would open if we should do so and should accept as 

 established laws which rest so largely upon negative reasoning. 

 The growing sentiment of the necessity of induction and of 

 inductive evidence is the least conspicuous, but really the most 

 important and lasting outcome of this prolonged discussion. 

 Weismann is the real initiator of this outcoming movement 

 although it has taken a radical direction he neither foresaw nor 

 advocated, for his position is eminently conservative. In fact 

 his first permanent service to Biology is his demand for direct 

 evidence of the Lamarckian principle, which has led to the 

 counter-demand for such evidence of his own Selection prin- 

 ciple, which by his own showing, and still more by his own 

 admission in this discussion with Spencer, he is unable to meet. 

 His second permanent service, as Professor Wilson reminds 

 the writer, is that he has brought into the foreground the rela- 

 tion between the hereditary mechanism and evolution. 



What have we gained in the controversy of the past decade 

 unless it is closer thinking and this keener appreciation of the 

 necessity for more observation } We carry forth, perhaps, 

 some new and useful working hypotheses as to possible modes 

 of evolution, and a fuller realization of the immense difficulties 

 of the heredity problem — but these are only indirect gains. 

 It is a direct gain that these negative results have led a 

 minority of biologists into a total reaction from speculation 

 and into a generally agnostic temper towards modern theories 

 which is far more healthy and hopeful than the confident spirit 

 of the majority upon either the Neo-Lamarckian or the Neo- 

 Darwinian side. There is no note of progress in the dogmatic 

 assertion that the question is established either as Spencer or 

 as Weismann would have it, unless this assertion can be backed 

 up by proof, and by whom can proof be presented if not by 

 these masters of the subject.? The conviction we all reach 

 when we sift wheat from chaff, and bring together from all 

 sources phenomena of different kinds and seek to discern what 

 the exact bearings of these phenomena are, is that we are still 

 on the threshold of the evolution problem, and that the secret 

 is largely tied up with that of vital phenomena in general. 

 The very wide and positive differences of opinion which pre- 



