VII.] TRANSMISSION OF ACQUIRED CHARACTERS, 401 



grcss of science. No one could have explained the useful 

 adaptations so common in animals and plants, before the li;^ht 

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

 mena ; at that time we should have been far from ri^ht 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. I first 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 diffif.ulties 

 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 of 

 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 idea is in reality insecure 



' Sec the second Essay. 



'^ (See i<. iMeJdola in Ann. and Mag. Nat. Hist., 1878, vol. i. pp. 

 158 /61. The author discusses many cases among insects in which 

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

 that instinct is to he ex [Gained by the principle of natural selection 

 which accounts for the other protective features. — E, B. I^.J 



^ [See ' Nature,' vol. 36, pp. 40 x 407. — E. B. P.] 



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

 Century' for April and May 1886. E. li. P.J 



Dd 



