188 NATURAL SCIENCE [September 



killed were taken at random without selection. Thus Darwin's 

 system contained its own refutation within itself. A later school 

 of evolutionists have maintained that the effects of habits or 

 conditions on the individual are not inherited, and therefore not 

 cumulative. According to this view, only those variations are 

 hereditary which arise in the germ, in the internal constitution of 

 the egg ; such variations are supposed to be numerous and to take 

 place in all possible directions, and natural selection is supposed to 

 pick out from among them those which are advantageous and so 

 accumulate them. I do not propose here to discuss the various 

 theories of heredity. The question of the possibility of the trans- 

 mission of acquired characters, or the determination of congenital 

 modifications by the direct influence of conditions is a very important 

 one, and has been much discussed. But I wish to draw attention 

 to a mode of considering the subject which is generally neglected, 

 namely, the inductive method. The doctrine of evolution is an in- 

 duction from the facts of zoology ; in my opinion conclusions con- 

 cerning the method and the causes of evolution can also be obtained 

 as inductions from a sufficiently wide survey of the phenomena. 



Every one will admit without hesitation that all variations must 

 be due to causes. But, according to the selectionists, hereditary 

 variations have no primary and essential relation to the require- 

 ments of life. Such variations occur in all or many directions 

 indefinitely, and they are so diverse that by the survival of a few 

 individuals out of the many that are generated, the complicated 

 adaptations which we know have been gradually produced. It is as 

 though we conceived of a table being produced by the process of 

 selecting from a large stock of pieces of wood of all shapes and 

 sizes, those which were of the shape and size required, and joining 

 them together ; and not by the usual process of sawing and planing 

 the various parts into shape out of a stock of planks all originally 

 similar. Thus selection preserves and combines the variations which 

 are most advantageous under the given conditions, but the relation 

 between the structure and the outer world has no hereditary effect 

 in moulding or shaping the structure. Eomanes maintained with 

 much truth that natural selection was a theory only of the origin of 

 adaptations, and not necessarily of the origin of species, but it is 

 further necessary to realise that it originates adaptations only in the 

 sense of preserving and combining the variations or modifications 

 which occur, and which happen to be advantageous. It may be 

 said to combine only in the sense of causing different variations in the 

 parents to be transmitted together to the offspring, and of allowing 

 new variations to occur only in the individuals which have survived. 



Now it is possible by actual observation to ascertain what 

 evidence there is, that variations which might by natural selection 



