62 An Examination of Weismannism. 



stable. In the former case, all the far-reaching 

 deductions which Weismann draws with reference to 

 the general theory of descent — or apart from the 

 more special problem of heredity — follow by way 

 of logical consequence. In the latter case, there is 

 no justification for any such deductions. For, no 

 matter how faintly or how fitfully the hereditary 

 qualities of the material in question may be modified 

 by the somatic-tissues in which it resides, or by 

 the external conditions of life to which it is exposed, 

 these disturbances of its absolute stability, and these 

 interruptions of its perpetual continuity, must cause 

 more or less frequent changes on the part of its 

 hereditary qualities — with the result that specific or 

 other modifications of organic types need not have 

 been solely due to the varying admixture of such 

 material in sexual unions on the one hand, or to the 

 unassisted power of natural selection on the other. 

 Numberless additional causes of individual variation 

 are admitted, while the Lamarckian principles are 

 still allowed some degree of play. And although 

 this is a lower degree than Darwin supposed, their 

 influence in determining the course of organic evolu- 

 tion may still have been enormous ; seeing that their 

 action, in whatever measure it may be supposed 

 to obtain, must always have been cumulative on the 

 one hand, and directive of variations in adaptive 

 lines on the other. Or, as Galton himself observes, 

 in the passage already quoted, ; " if they exist, in how- 

 ever faint a degree, a complete theory of heredity 

 must account for them." He saw, indeed, that a most 

 inviting logical system could be framed by denying 

 that they can ever exist in any degree — or, in 



