i6 Darwin, and after Darwin. 



law of acceleration and retardation." In all these 

 cases, so far as I can see, the so-called explanations 

 are not in fact any explanations ; but either a mere 

 re-statement of the facts, or else an enunciation of 

 more or less meaningless propositions. Thus, when 

 it is said that the evolution of any given type has 

 been due to the " acceleration of growth-force " with 

 respect to some structures, and the "retardation of 

 growth-force" with respect to others, it appears 

 evident that we have not any real explanation in terms 

 of causality; we have only the form of an explanation 

 in the terms of a proposition. All that has been done 

 is to express the fact of evolution in somewhat obscure 

 phraseology, since the very thing we want to know 

 about this fact is — What are the causes of it as a fact, 

 or the reasons which have led to the increase of some 

 of the parts of any given type, and the concomitant 

 decrease of others ? It is merely the facts themselves 

 that are again presented by saying that the develop- 

 ment has been in the one case accelerated, while in 

 the other it has been retarded ^. 



So much for what may be termed this New 

 World theory of the origin of species: it is a mere 

 re-statement of the facts. Mr. Geddes' theory, on the 



' Take, for example, the following, which is a fair epitome of the 

 whole: — "I believe that this is the simplest mode of stating and 

 explaining the law of variation ; that some forms acquire something 

 which their parents did not possess; and that those which acquire 

 something additional have to pass through more numerous stages than 

 their ancestors ; and those which lose something pass through fewer 

 stages than their ancestors ; and these processes are expressed by the 

 terms "acceleration " and "retardation " {Origin of the Fittest, pp. 125, 

 226, and 297). Even if this be "the simplest mode of stating the law 

 of variation," it obviously does nothing in the way of explaining the 

 law. 



