426 ON SUPPOSED DOTAXICAL PROOFS OF [VII. 



the secondary ones which owe their appearance to variations 

 in the germ, however such variations may have arisen. We 

 have hitherto been accustomed to call the former 'acquired 

 characters,' but we might also call them '' soinatogcnic,' because 

 they follow from the reaction of the soma under external 

 influences ; while all other characters might be contrasted as 

 ' blastogenic^ because they include all those characters in the 

 body which have arisen from changes in the germ. In this way 

 we might perhaps prevent the possibility of misunderstanding. 

 We maintain that the '' soniafogoiic' characters cannot be 

 transmitted, or rather, that those who assert that they can be 

 transmitted, must furnish the requisite proofs. The somatogenic 

 characters not only include the effects of mutilation, but the 

 changes which follow from increased or diminished performance 

 of function, and those which are directly due to nutrition and 

 any of the other external influences which act upon the body. 

 Among the blastogenic characters, we include not only all the 

 changes produced by natural selection operating upon varia- 

 tions in the germ, but all otlier characters which result from 

 this latter cause. 



If we now wish to place Hoffmann's results in their right 

 position, we must regard all of them as ^ blastogenic' characters, 

 for no one of them can be considered as belonging to the group 

 which has been hitherto spoken of as 'acquired,' in the 

 literature of evolution : they are not due to sofnafogi'/iic but to 

 blastogcnic changes. The body of the plant— the soma—hsis 

 not been directly affected by external influences, in Hoffmann's 

 experiments, but changes have been wrought in the germ- 

 plasm of the germ-cells and, only after this, in the soma of 

 succeeding generations. 



There is no difficulty in finding facts in support of this state- 

 ment, among Hoffmann's experiments. The proof chiefly lies 

 in the fact that in no one of his numerous experiments did any 

 change appear in the first generation. The seeds of different 

 species of wild plants, with normal flowers, were cultivated in 

 the garden and in pots (thickly sown in the latter case), but no 

 one of the plants produced by these wild seeds possessed a 

 single double flower. It was only after a greater or less 

 number of generations had elapsed that a variable propor- 

 tion of double flowers appeared, sometimes accompanied by 



