242 INDUCTION OF 



in the various tribes of animals, doubtless, in part 

 depend. 



Nothing can more strikingly confirm this view 

 than the difference of the vegetable structures which 

 respectively accompany the vinous and acetous fer- 

 mentations. Special modes of chemical action will 

 alone maintain specific forms of life. 



Srdly. The vitalization of the elements of the food 

 is effected, not through the medium of its sponta- 

 neous decomposition, but by more energetic chemical 

 changes wrought by the digestive fluids. The vital 

 motion is conditional upon a decomposing motion 

 intensified by contact with the products of secretion. 



Parallel instances are not wanting. Muscles waste 

 unless their decomposition be rendered more rapid 

 by those influences which bring them into functional 

 activity. Plants attain no vigour unless decomposi- 

 tion be hastened in their leaves by light. And the 

 earliest changes in the embryo, " consisting in the 

 formation of a membrane upon the exterior, while a 

 large part of the included substance undergoes lique- 

 faction," indicate the operation of the same law. 

 The phenomena of inflammation fall into the same 



