182 THE DIRECT INFLUENCE 



that he has occasionally attended to this subject from his 

 youth. ... I am very glad he has called attention to 

 galls: this has always seemed to me a profoundly in- 

 teresting subject; and if I had been younger would take 

 it up.' 



" His interest in this subject was connected with his 

 ever-present wish to learn something of the causes of 

 variation. He imagined to himself wonderful galls 

 caused to appear on the ovaries of plants, and by these 

 means he thought it possible that the seed might be 

 influenced, and thus new varieties arise. He made a 

 considerable number of experiments by injecting 

 various reagents into the tissues of leaves, and with some 

 slight indications of success." ^ 



In response to a request for a more detailed 

 account of work that may have been done on this 

 subject by the elder Darwin, Professor Francis 

 Darwin writes under date of November 27, 

 1908:— 



" I am sorry that I can give you no further informa- 

 tion about the experiments on galls. My recollection 

 is that we tried only injections with leaves and stems, 

 and that no actual experiments were made on ovaries. 

 I have never looked at his notes and do not know where 

 they are at this moment, but I feel pretty sure that no 

 definite results were obtained. I think acetic or formic 

 acid was used in the experiments." 



In the course of my extensive cultures dealing 

 with mutations, the theoretical conclusions of 

 De Vries as to the pre-mutation period came up 

 for serious consideration, and in order to obtain 

 some evidence upon this point, as well as to test 

 the assumption that the actual changes upon 



' Life and Letters of Charles Darwin, by P. Darwin, II, p. S17, 

 1905. New York. 



