224 THE LAW OF JOHANNSEN. 



of Stout with Coleus iurnishes evident examples of both pro- 

 cesses. 



And next come all the facts, which show changes in the char- 

 acters of series of organisms, which are obviously not de- 

 pendent upon rearrangement of the personnel of the genes, 

 but appear to take place in geno-typically pure material as 

 well as in impure. Do they tend to make us believe in a qualit- 

 ative change in the genes themselves? 



The tacts in this group are a rather miscellaneous collect- 

 ion, bien etonnes de se trouver ensemble. On one end come 

 the experiments with the inheritance of red colour produced 

 by ingestion of a red dye. We can see how this dye is handed 

 on in pure material as well as in hybrids. But would anybody 

 suppose such a transmission of a character to be due to quali- 

 tative changes in a gene? Next come the experiments per- 

 formed at the Viennese Vivarium, by Przibram and Kammerer, 

 in which mice with long tails as the result of life in a hot envir- 

 onment have long-tailed off-spring in the same hot room, and 

 the transmission of a changed colour in lizards already discus- 

 sed. And we think, that the experiments of Root and Jennings 

 and Middleton belong to this class, because the material is of 

 such a nature as to make probable the direct transmission of 

 properties of cells, both properties different from the mode 

 through action of the environment, and properties induced by 

 quantitative fluctuations in the amount of individual genes 

 present. 



As we said above, there is no "pure line theory." And the 

 pure line conception has no connection with evolution, at 

 least no direct one. Root in his paper on Contropyxis sees 

 two alternatives to bring his experiments into line with the 

 "pure line" hypothesis. In the first place he thinks, it is pos- 

 sible to explain every instance of the effectof selection within 

 pure clones of uni-cellulars by an individual explanation, like 

 Morgan's attempt to explain inheritance of variations by 

 assuming somatic segregations at the cell-divisions. In the 

 second place Root thinks, we might assert, that the pure line 



