116 DARWINISM AND HUMAN LIFE 



that the influence was operative. Here, then, we 

 have definite evidence of germinal variation 

 evoked by environmental stimulus. 



Very interesting, also, are the experiments of Dr. 



C. S. Gager, who exposed the egg-cells and pollen- 

 cells of Onagra biennis to Radium rays, and found 

 that plants grown from the seeds produced under 

 this influence were very different from the parents, 

 and that the change persisted to the second genera- 

 tion at least. Here, again, there is proof of heritable 

 variation induced by environmental stimulus. 



Shortly before his death Darwin began to 

 experiment on the possibility of producing galls 

 artificially. " He imagined to himself wonder- 

 ful 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."' What Darwin just began 

 has been carried out with great skill by Prof. 



D. T. MacDougal. " Among other operations, 

 solutions of sugar, calcium, potassium, and zinc 

 were injected by the use of hypodermic syringes 

 into the developing ovaries of Raimannia, one of 

 the evening primroses, early in 1905, with the 

 result that, out of several hundreds of seeds borne 

 by the treated ovaries, sixteen individuals were 

 found to be notably atypic, among other char- 

 acters lacking the trichomes which are so con- 

 spicuous with the parental form. These reproduced 

 themselves in the second and third generations, 

 coming true to the newly-assumed characters."^ 

 Similar experiments were made with (Enothera 



i " Life and Letters of Charles Darwin," vol. ii. p. 517. 

 a "The Direct Influence of Environment," by D. T. Mac- 

 Dougal, in " Fifty Years of Darwinism " (1909). 



