MENDEL'S METHOD 19 



Of even greater interest, however, are the more 

 strictly experimental researches which have been 

 published during the present century. In the first 

 place , we have the observations of de Vries, who has 

 introduced a new method of study that of cultivating 

 great numbers of seedling plants with the object of 

 discovering definite new forms or mutations among 

 their number. Lastly, and in its results much 

 the most important of all, we have the method of 

 Mendel, published half a century ago, but only re- 

 cently brought into prominence owing to its redis- 

 covery and confirmation by three independent workers 

 Correns, Tschermak, and de Vries. This method 

 consists in the cross breeding of strains of plants or 

 animals which differ in definite characters, and in the 

 statistical examination of the proportions in which 

 these characters appear among the offspring obtained 

 from the crosses. 



Further experiments on the lines which Mendel in- 

 dicated bid fair to revolutionize within a few years the 

 arts of the breeders of plants and animals. This is 

 due to the fact that such experiments are leading to 

 the introduction into these pursuits of a degree of 

 scientific exactness which was previously altogether 

 unforeseen. The change in our ideas regarding the 

 method of hereditary transmission of characters, which 

 has resulted from these experiments, has been aptly 

 compared with the change brought about in men's 

 understanding of the science of chemistry by 

 Dalton's conception of the atom. For the rest the 

 new experiments tend on the whole to confirm the 



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