The Decisive Experiment 173 



perature, light or darkness, particular substances that are 

 nutritive, stimulating or poisonous, infections, immuniza- 

 tions, etc., could never afford such incontestable evidence 

 against Weismann's theory, as those investigations which 

 employ agents having a very definitely localized action. 



Thus for example Heschenhagen's researches upon 

 the adaptability of the lower fungi to sodium chloride 

 have, for the reasons stated, little or no value for the 

 refutation of Weismann's theory, even though they have 

 proved that the spores of the mycelium which had 

 adapted itself to a strongly concentrated saline solution 

 were capable of germinating in concentrations in which 

 the spores of a mycelium arising in normal conditions 

 were incapable of germinating. The same is true for 

 the similar researches carried on by Hunger-Errera, 

 DeMeyer, Pulst and Ray upon the inheritance of changes, 

 mostly physiological rather than morphological in nature, 

 which were brought about in the lower fungi by means 

 of concentrated salt solutions, for example by sodium 

 chloride or copper sulphate or concentrated sugar solu- 

 tions, although these results as well as Heschenhagen's 

 are certainly very interesting from the point of view of 

 the adaptability of organisms to their environment. 



Also Hoffman's researches upon the inheritance of 

 variations produced by insufficient nourishment in 

 Papaver, Migella, and Argemone, (a relatively large 

 number of atypical flowers), and Schubeler's researches 

 upon the inheritance of the more rapid development of 

 barley grains which had been transplanted from the south 

 part of Norway to the north part, prove incontrovertibly 

 the inheritance of the changes induced in organisms 

 through general conditions in their environment, but the 

 general influences very probably exerted in those cases also 



