130 PROBLEMS OF EVOLUTION 



doubt, act directly upon the reproductive cells, not indirectly 

 through the organism as a whole. If a wild plant is moved to a 

 garden, it will often grow there for years without any modifica- 

 tion showing itself. Probably in the first generation of seedlings 

 from it there will be no variations. Only after several generations 

 will a tendency to vary display itself, and then the new character 

 will very probably be such as to convince us that the environ- 

 ment has not adapted the plant to itself nor the plant adapted 

 itself to the environment. Hoffmann, the German botanist, 

 planted poppies very thickly together, and he found that after 

 several generations some produced double flowers ; in some 

 cases the double flowers reappeared in the seedlings from these, 

 even though they were allowed ample space. In fact, change of 

 circumstances stimulated the reproductive cells to vary, and the 

 variations sometimes reappeared even when the normal conditions 

 were restored. This is all that can be said. But experimenters 

 are often so delighted with their experiments that they run riot 

 in the theories they build upon them. In this case there was no 

 adaptation, since a double-flowered plant is no better off when 

 jammed together with others than a single-flowered plant. I am 

 surprised, therefore, that Lamarckians should make so much of 

 these experiments, as if their theory had received a decisive 

 confirmation. To make good their case they must prove two 

 things: (l) That a new character is caused by the environment ; 

 (2) that the character is inherited. To take the second point 

 first, the transmission of the doubleness is not proved; a con- 

 dition of instability had been brought about, and there was still 

 some shifting from single to double and from double to single. 

 When variation has once begun it is likely to continue, as 

 gardeners know. As to the other point, we must distinguish 

 between causation and mere stimulation. If the environment 

 causes a variation, surely an adaptation must ensue. But here 

 it has only been what the spur is to the horse, the stimulus 

 that leads him, being constituted as he is, to gallop. "When varia- 

 tions arise, as in the poppies, in response to a stimulus from 

 without, Natural Selection must come in before adaptation is 

 effected. Thus the attempt to banish Natural Selection only 



