268 THE AMERICAN NATURALIST [VOL. XLIII 



of intracellular pangenesis has never received the logical 

 development that characterizes Weismann's theory of 

 the germ plasm and is considerably inferior to the latter 

 as a scholastic production. The explanation it affords 

 of the alleged distinction between varieties and elemen- 

 tary species is, as we have seen, practically no explanation 

 at all. The theory may be consistent with the facts of 

 Mendelian inheritance and the supposed independent 

 variability of parts, but why it should lead one to antici- 

 pate that elementary species differing from the parent 

 throughout their organization originate by a single sud- 

 den leap is not so clear. Rather it would lead one to 

 expect that organisms would be modified, a part here and 

 a part there, corresponding to the independently variable 

 elements determined by particular pangens, of which there 

 are numerous kinds, until the whole was slowly trans- 

 formed. De Vries, however, is careful to explain that a 

 single pangen may be responsible for certain characters 

 found in various parts of the organism, such as the color 

 of leaves, flower and fruit, and that pangens are supposed 

 to influence each other's manifestation so that a variation 

 in a single pangen may have a far-reaching effect. In 

 a chapter on the association of characters in his recent 

 book on Plant Breeding a great deal of emphasis is laid 

 upon the value of a study of the correlation of the dif- 

 ferent parts of the plant. He says : 



We come to the conception of a general interdependency of all 

 parts, organs and qualities of an organism. They are governed more 

 or less by the same laws which cause them to undergo corresponding 

 changes when subjected to the same influences. 



It seems to me that the author is here upon treacherous 

 ground. Through the assumption of manifold correla- 

 tions De Vries attempts to account for a change in a 

 single pangen which has to do primarily with one inde- 

 pendently variable part of the organism producing a 

 modification of the organism as a whole, but in so doing 

 he is taking the foundation away from the argument upon 

 which the justification of the pangen assumption rests. 



