VII.] TRANSMISSION OF ACQUIRED CHARACTERS. 401 



gress of science. No one could have explained the useful 

 adaptations so common in animals and plants, before the light 

 of the theory of natural selection had fallen on these pheno- 

 mena ; at that time we should have been far from right if we 

 had assumed that organisms possess a power which causes 

 them to respond to external influences by useful modifications, 

 a power unknown elsewhere, entirely unproved and only sup- 

 ported by the fact that at that time it did not seem possible to 

 explain the phenomena in any other way. 



Although my theory has not been disproved, I will never- 

 theless attempt to bring into further accordance with it certain 

 phenomena which seem at first sight to oppose it. 1 lirst began 

 to take this course in my paper ' On Heredity '.' In that paper 

 I attempted to show how the fact that disused organs become 

 rudimentary may be readily explained without assuming the 

 transmission of acquired characters; and also that the origin of 

 instincts may in all cases be referred to the process of natural 

 selection'-, although many observers had followed Darwin in 

 explaining them as inherited habits,— a view which becomes 

 untenable if the habits adopted and practised in a single life 

 cannot be transmitted. 



Other phenomena which appeared to present difficulties 

 were also considered and brought into accordance with the 

 theory, and I think that I have been successful in showing that 

 adequate and simple explanations may be given. 



There certainly remain many phenomena which seem to be 

 opposed to my theory and for which a new explanation must 

 be found. Thus Romanes^, following Herbert Spencer*, has 

 recently pointed to the phenomena of correlation as a proof ol 

 the transmission of acquired characters ; but, at no distant time, 

 I hope to be able to consider this objection, and to show that 

 the apparent support given to the old jdea is in reality insecure 



^ See the second Essay. 



2 [See R. Meldola in Ann. and Mag. Nat. Hist., 1878, vol. i. pp. 

 158-161. The author discusses many cases among insects in wliich 

 instinct is related to protective structure or colouring: he also considers 

 that instinct is to be explained by the principle of natural selection 

 v^hich accounts for the other protective features. — E. B. P.J 



^ [See ' Nature,' vol. 36, pp. 401 407.— E. B. P.] 



* [See ' The Factors of organic Evolution ' in ' The Nineteenth 

 Century ' for April and May 1886.— E. B. P.J 



Dd 



