BIOLOGICAL TRAINING 507 



827. The question arises whether the attitude of those syste- 

 matists who have 'kept aloof from speculation can be justified. 

 Here speculation means nothing other than an attempt to link 

 together facts concerning animals and plants in chains of causation. 

 Of course, speculation may be what even students of other sciences 

 consider illegitimate ; that is, it may be founded on data which 

 have not been verified, or it may be conducted by thinking which 

 I is not tested. But no such considerations seem to have guided 

 the system atists that 'kept aloof; for, as their aloofness implies, 

 they did not attempt to impugn either the facts or the thinking, 

 and they preserved the aloofness even after the actual occurrence 

 of Natural Selection and of evolution consequent on it was 

 demonstrated amongst men, the only living beings with whose 

 lives they were at all intimately acquainted. It is not alleged that 

 their attitude was due to lack of time, or of interest, or of knowledge 

 of the facts. Apparently they have been guided by the more or 

 less clearly formulated notion that science is created, not by ascer- 

 taining chains of causation, but solely by classifying facts according 

 to co-existences and resemblances. Whether they are right or 

 wrong is, in the absence of any attempt at demonstration by them, 

 a matter of opinion ; but it is worthy of notice that that which is 

 condemned by them is, in effect, not merely the science of Darwin, 

 but also that of Bacon and Newton, not merely the theory of 

 Natural Selection, but also mathematics in its entirety, physics 

 almost in its entirety, and astronomy in the best part of its extent. 

 It is worthy of notice also, that unless human beings linked together 

 in chains of causation the facts they learn during the ordinary 

 course of their lives they would not be rational beings, and could 

 not maintain existence. The circumstance that they are able 



mates, the differences selected would not be impalpable. It is true that, if we 

 arranged all the members of a variety in a row in the order of their heights or 

 strengths we should, as a rule, find the differences between each individual and 

 his next neighbours very small. But nature would do nothing of the kind. On 

 the contrary, she would simply select for survival, as a general rule, the especially 

 tall and strong, and for elimination the especially short and weak. Forms inter- 

 mediate between living types actually abound forms that are intermediate 

 between one kingdom and another, one class and another, one order and another, 

 one species and another, or one variety and another. No selectionist believes that 

 all the links have survived or are known. The complete chain could be recon- 

 structed only if every generation were known to us. Mutationists do not doubt 

 that the organic world has arisen by evolution. But their links are missing 

 equally with those of the selectionists ; for none will maintain that the vast gaps 

 which exist between many living types and their nearest known relations, gaps 

 which involve thousands of co-ordinated changes, can ever have been crossed by 

 a single leap. 



