igo PRESENT-DAY RATIONALISM 



try to combine both. One is Inductive, the other Experi- 

 mental evidence. Now, I seem to notice that it is mainly 

 zoologists who deny that "acquired characters" are hereditary. 

 Whether this is because they lay little or no value on inductive 

 evidence — at all events, they do not always realise the fact that 

 sufficient inductive evidence requires no experimental proof in 

 addition — or whether it be because animals do not lend them- 

 selves so readily to experimental verification as plants, I cannot 

 undertake to say. The latter, however, as it seems to me, afford 

 overwhelming proof along both lines of evidence. I shall give, 

 therefore, what I regard as convincing examples of both 

 methods, thereby demonstrating the heredity of acquired 

 characters. 



First, with regard to experimental verification. Darwin 

 based his theory mainly on observations upon Animals and 

 Plants U7ider Domestication^ which he published in two volumes 

 with this title. 



I will therefore take one or two cases from the cultivation 

 of plants. 



If seed of the wild radish, carrot, parsnip or cabbage be 

 collected and we sow them in a well-prepared garden soil they 

 will all grow very vigorously. They need not be crowded ; 

 and at the end of the season the roots of the first three kinds 

 instead of being slender in size but tough and wiry in texture 

 will be found to have "acquired " a certain degree of fleshiness. 

 Taking seed from one such plant and sowing it as before, 

 under the same conditions, the roots of the second generation 

 will be larger than those of the first generation ; an increment 

 has been added to what was acquired by the first generation. 

 Repeating this process for some five or six generations a fine 

 kitchen-garden "root" will be obtained. It will then have 

 become "fixed," having arrived at what may be called the 

 " average maximum " size. 



Such, then, is an experimental proof of the heredity of 

 acquired "somatic" or "vegetative" characters. 



Similar experimental proof is applicable to all root crops, 



