82 BIOLOGICAL LECTURES. 



lar feeling has been voiced by Romanes and others, and quite 

 lately by Scott ; l but the most extreme expression of it has 

 recently come from Driesch 2 in his implication that there is a 

 factor not only unknown but unknowable ! 



Theoretically neither of these five hypotheses of the day ex- 

 cludes the others. They may all cooperate. The role which 

 each plays, or the fate of each in the history of speculation 

 largely or wholly depends upon the solution of the problem of 

 the transmission or non-transmission of acquired variations and 

 after all that has been written on this question this must be 

 regarded by every impartial observer as still an open one. 



We are far from finally testing or dismissing these old factors, 

 but the reaction from speculation upon them is in itself a silent 

 admission that we must reach out for some unknown quantity. 

 If such does exist there is little hope that we shall discover it 

 except by the most laborious research ; and while we may 

 predict that conclusive evidence of its existence will be found 

 in morphology, it is safe to add that the fortunate discoverer 

 will be a physiologist. 



THE ANALYSIS OF VARIATION. 



After this introductory survey let us consider as another 

 outcome of the controversy that Variation and the related 

 branch of research, Experimental Evolution, are now in the 

 foreground as the most important and hopeful of the many 

 channels into which the inductive tests of known or unknown 

 factors may be turned. Let us make an honorable exception 

 of those reactionists, such as Bateson 3 and Weldon, who have 

 instituted an exact investigation into the laws of Variation. 



How shall the study of Variation be carried on ? I totally 

 differ at the outset from. Bateson in the standpoint taken in the 

 introduction of his work, that the best method of starting such 

 an investigation is in discarding the analysis which rests upon 

 the experience as well as the more or less speculative basis of 



1 On Variations and Mutations. Am. Jorir. Sc., November, 1894. 



2 Analytische Theorie der Organischen Entwickelung. Leipsic, 1894. 

 8 W. Bateson : Materials for the Study of Variation. London, 1894. 



