148 THE INDUCTIONS OF BIOLOGY. 



w^hich this increasing contrast sliows itself, bear variable 

 ratios to each other, does not conflict with the general truth> 

 that as we ascend in the hierarchy of organisms, we meet with 

 not only an increasing differentiation of parts, but also an 

 increasing differentiation from the surrounding medium in 

 sundry other physical attributes. It would seem that this 

 peculiarity has some necessary connexion with superior 

 vital manifestations. One of those lowly gelatinous forms, 

 so transparent and colourless as to be with difficulty dis- 

 tinguished from the water it floats in, is not more like its 

 medium in chemical, mechanical, optical, thermal, and other 

 properties, than it is in the passivitj^ with which it sub- 

 mits to all the influences and actions brought to bear upon 

 it ; while the mammal does not more widely differ from 

 inanimate things in these properties, than it does in the ac< 

 tivity with which it meets surrounding changes by compens- 

 ating changes in itself. And between these two extremes, 

 we shall observe a constant ratio between these two kinds of 

 contrast. Whence we may say, that in proportion as an 

 organism is physically like its environment, does it remain a 

 passive partaker of the changes going on in its environment ; 

 while in proportion as it is endowed with powers of counter- 

 acting such changes, it exhibits greater unlikeness to its en- 

 vironment.* 



If now, from this same point of view, we consider the rela- 

 tion borne to its environment by any superior organism in 

 its successive stages, we find an analogous series of con- 

 trasts. Of course in respect of degrees of structure, the 

 parallelism is complete. The difference, at first small, be- 

 tween the comparatively structureless germ and the com- 

 paratively structureless inorganic world, becomes necessarily 

 greater, step by step, as the differentiations of the germ be- 

 come more numerous and definite. How of form 

 the like holds, is equally manifest. The sphere, which is 



* This paragraph originally formed part of a review-article on '■ Transcenden« 

 tal Physiology," publigiied in 1857 



