x THE STUDY OF EVOLUTION 



He who is concerned at arriving at the truth is impatient of such 

 labels : it is the truth he seeks, not the confirmation of the views 

 of any one predecessor, however great be the admiration for his 

 work and however large the debt he owes to him. 



Yet as regards the ancient controversy, this perhaps should 

 be said, that in so far as between Darwin and Lamarck the 

 essence of the teaching of the latter is that variation is an active 

 process, a reaction on the part of living matter to its environment, 

 the conclusions reached in these pages undoubtedly favour the 

 Lamarckian view. Nevertheless, to accept them does not mean 

 that the principle of natural selection is thereby excluded, or that 

 the two principles are mutually antagonistic, but only that the 

 influence of external forces is the primary process in the produc- 

 tion of variation, and that natural selection is secondary, culling 

 out those grades and forms of variation which are least economical 

 and represent the less perfect adaptation on the part of individuals 

 to the conditions in which the family or species finds itself for 

 the time being. Seen thus, evolution, whether what we regard 

 as progressive or as regressive, is the outcome of an active 

 process of continuous adjustment between organisms and their 

 environment. 



The survival of the fittest, it will be seen, does not depend 

 upon chance variation. A given environment leads to variation 

 in a particular direction, provided that the change in sur- 

 roundings is not so great as to be beyond the adaptive powers 

 of the organism. Where " chance " enters is in the nature of 

 the new environment to which the individual, and the race, 

 may be exposed. To the extent that the individual is unable 

 to control his surroundings, to that extent is the race exposed 

 to chance. It does not appear to have been sufficiently realized 

 hitherto that here essentially it is that chance is operative. 

 Conjugation and amphimixis, it is true, are a cause of individual 

 variation, but from the point of view of the race are distinctly 

 conservative processes, tending to maintain the mean. 



When the first of the series of Croonian Lectures was pub- 



