232 NATURAL SCIENCE [April 



discoverer ; for discovery requires the creative effort of the imagina- 

 tion. The scientific man does not stumble upon new facts or con- 

 clusions by accident ; he finds vs^hat he looks for. The problem 

 before him is essentially similar to that of the historian who tries 

 to create an accurate and complete picture of an epoch out of 

 scattered records of contemporary impressions more or less true, 

 and none wholly true. Fertility of the imagination is absolutely 

 essential for that step, from the less to the more perfectly known, 

 which we call discovery. 



" But fertility of imagination alone is insufficient for the highest 

 achievement in poetry, history, or science ; for in all these subjects 

 the strictest self-criticism and the soundest judgment are necessary 

 in order to insure that the results are an advance in the direction of 

 truth." 



This passage appears to me to be singularly applicable to 

 evolutionists of the present day. If an examination of the facts, 

 collected by evolutionists with reference to heredity, be made, it 

 will be found that in most cases elimination of doubtful factors has 

 not been attempted, because it has been assumed that variations 

 must be adaptive or non-adaptive in character, and that consequently 

 the case for or against use-inheritance will be decided by thus 

 directly appealing to variations as they exist in nature rather than 

 to specially prepared test cases. The aim of this paper is to 

 endeavour to demonstrate that this question cannot be so settled, 

 even if it were always possible to know whether a given variation 

 were adaptive or otherwise. And when it is considered how 

 difficult it is and what prolonged study is required to assert whether 

 any small variation in man is useful or otherwise, the difficulty of 

 arriving at a similar conclusion in any other sub-order or species, 

 which of necessity is much less thoroughly studied, must be 

 immense. 



If a statement of the views held by diflferent evolutionists be 

 compared with objections raised to these views, the inconclusiveness 

 of the objections will be noticed in most if not all the cases so 

 examined. 



If the opinions of Cope, Henslow, Darwin, or Weismann on this 



subject be shortly stated, the difficulty of arriving at a satisfactory 



conclusion will be rendered still more obvious, while the intermediate 



positions held by other evolutionists, such as Spencer, Huxley, 



Romanes, Gal ton, make the present position peculiarly unsatisfactory 



for future work in evolution until this question is settled. 



Darwin. — " As far as I am able to judge, after long attending to 



the subject, the conditions of life appear to act in two ways, — 



directly on the whole organism or on certain parts alone, and 



indirectly by affecting the reproductive system. With respect 



