674 Studies in the Theory of Descent. 



himself has correctly designated it. Herein is 

 evidently comprised the total morphology of the 

 organism the structure as a whole, the length, 

 thickness and weight of the single parts, as well 

 as the histological structure of the tissues, since 

 upon all these depends the performance of the 

 single parts. But when, under correlation, Von 

 Hartmann comprises " also a morphological, 

 systematic, inter-action of all the elements of the 

 organism with reference both to the typical 

 ground-plan of the organization as well as to the 

 microscopic anatomical structure of the tissues," 

 he drags into the idea something foreign to it, not 

 on the ground of facts, but actually in opposition 

 to them, and supported only by a supposed 

 " innate developmental principle" which "is not 

 of a mechanical nature." 



The living organism has already been often 

 compared with a crystal, and the comparison is, 

 mutatis mutandis, justifiable. As in the growing 

 crystal the single molecules cannot become 

 joined together at pleasure, but only in a fixed 

 manner, so are the parts of an organism governed 

 in their respective distribution. In the crystal 

 where nothing but homogeneous parts become 

 grouped together their resulting combination is 

 likewise homogeneous, and it is obvious that they 

 offer but very little possibility of modification, so 

 that the governing laws thus appear restricted 

 and immutable. In the organism, whether re- 



