142 Darwin, and after Darwin. 



schools, chiefly composed of individual members who 

 agree with each other only to the extent of holding 

 that the causal agency of natural selection is not so 

 great as Darwin supposed. The Duke of Argyll, 

 Mr. Mivart, and Mr. Geddes may be named in this 

 connexion ; together with the self-styled neo- 

 Lamarckians, who seek to magnify the Lamarckian 

 principles at the expense of the distinctively Dar- 

 winian. 



This primary difference of opinion leads deductively 

 to certain secondary differences. For if a man starts 

 with the premiss that natural selection must neces- 

 sarily be the " exclusive " cause of organic evolution, 

 he is likely to draw conclusions which another man 

 would not draw who starts with the premiss that 

 natural selection is but the " main " cause. Of these 

 subordinate differences the most important are those 

 which relate to the possible transmission of acquired 

 characters, to the necessary (or only general) utility 

 of specific characters, and to the problem touching the 

 inter-sterility of allied species. But we may well 

 hope that before another ten years shall have passed, 

 even these still outstanding questions will have been 

 finally settled ; and thus that within the limits of an 

 ordinary lifetime the theory of organic evolution will 

 have been founded and completed in all its parts, to 

 stand for ever in the world of men as at once the 

 greatest achievement in the history of science, and the 

 most splendid monument of the nineteenth century. 



In the later chapters of the foregoing treatise I have 

 sought to indicate certain matters of general principle, 

 which many years of study specially devoted to this 

 great movement of contemporary thought have led 



