462 Mutations 



aspect of the subject, including the general pedi- 

 gree of the animal and vegetable kingdom, may 

 be said to have been outlined by Darwin and his 

 followers, but this phase of the subject lies be- 

 yond the limits of our present discussion. 



The other phase of the problem is concerned 

 with the manner in which the single elementary 

 species and varieties have sprung from one an- 

 other. There is no reason to suppose that the 

 world is reaching the end of its development, 

 and so we are to infer that the production of 

 new species and varieties is still going on. In 

 reality new forms are observed to originate 

 from time to time, both wild and in cultivation, 

 and such facts do not leave any doubt as to their 

 origin from other allied types, and according to 

 natural and general laws. 



In the wild state, however, and even with cul- 

 tivated plants of the field and garden, the condi- 

 tions, though allowing of the immediate obser- 

 vation of the origination of new forms, are by no 

 means favorable for a closer inquiry into the 

 real nature of the process. Therefore I shall 

 postpone the discussion of the facts till an- 

 other lecture, as their bearing will be more 

 easily understood after having deal% with more 

 complete cases. 



These can only be obtained by direct experi- 

 mentation. Comparative studies, of course, 



