RECONVERSION OF ORGANIC FORCES. 419 



The decay which is continually going on during the life 

 of a Plant restores to the inorganic world, in the form of car- 

 bonic acid, water, and ammonia, a part of the materials drawn 

 from it in the act of vegetation ; and a reservation being made 

 of those vegetable products which are consumed as food by 

 Animals, or which are preserved (like timber, flax, cotton, 

 &c.) in a state of permanence, the various forms of decom- 

 position which take place after death complete that restora- 

 tion. But in returning, however slowly, to the condition of 

 water, carbonic acid, ammonia, &c., the constituents of 

 Plants give forth an amount of heat equivalent to that which 

 they would generate by the process of ordinary combustion ; 

 and thus they restore to the inorganic world, not only the mou- 

 terials, but the forces, at the expense of which the vegetable 

 fabric was constructed. It is for the most part only in the 

 humblest Plants, and in a particular phase of their lives, that 

 such a restoration takes place in the form of motion, this mo- 

 tion being, like growth and development, an expression of the 

 vital activity of the "Zoospores" of Algo3, and being ob- 

 viously intended for their dispersion. 



Hence we seem justified in affirming that the Correlation 

 between heat and the organizing force of Plants is not less 

 intimate than that which exists between heat and motion. 

 The special attribute of the vegetable germ is its power of 

 utilizing, after its own particular fashion, the heat which it 

 receives, and of applying it as a constructive power to the 

 building-up of its fabric after its characteristic type. 



