154 Darwin, and after Dai-win. 



the Lamarckian principles cannot obtain), but require 

 to be actively used, in that proportion does it become 

 difficult to understand the incipient construction 

 of them by natural selection alone. Therefore, in 

 many such cases, if the incipient construction is 

 not to be explained by the Lamarckian principles, 

 it is difficult to see how it is to be explained at all. 



Furthermore, since the question as to the trans- 

 mission of acquired characters stands now exactly 

 as it did after the publication of Mr. Galton's 

 Theory of Heredity twenty years ago, it would seem 

 that our judgement with regard to it should remain 

 exactly what it was then. Although we must 

 " out-Darwin Darwin " to the extent of holding 

 that he assigned too large a measure of intensity 

 to the Lamarckian factors, no sufficient reason 

 has been shown for denying the existence of 

 these factors in toto ; while, on the other hand 

 there are certain general considerations, and certain 

 particular facts, which appear to render it prob- 

 able that they have played a highly important 

 part in the process of organic evolution as a whole. 

 At the same time, and in the present state of 

 our information, this judgement must be deemed 

 provisional, or liable eventually to be overturned 

 by experimental proof of the non-inheritance of 

 acquired characters. But. even if this should ever 

 be finally accomplished, the question would still 

 remain whether the principle of natural selection 

 alone is capable of explaining all the facts of adap- 

 tation ; and, for my own part, I should then be 

 disposed to believe that there must be some other, 

 though hitherto undiscovered, principle at work, 



