2S DISEASE IN PLANTS. 



The question now arises, how is this relatively 

 enormous gain in energy employed by the plant ? 

 Our answer to the question is not complete, but 

 modern discoveries in various directions have 

 supplied clues here and there which enable us to 

 sketch in some degree the kinds of changes that 

 must go on. 



Not the least startling result is that, important 

 as carbon-assimilation is as the chief mode of 

 supplying energy, it is not the only means that 

 the plant has of obtaining such from the environ- 

 ment, and it is even possible not to say 

 probable that energy from the external universe 

 may be conveyed into the body of the plant in 

 forms quite different from those perceptible to our 

 eyes as light. 



In the most recent survey of this domain, 

 it is pointed out that we may distinguish between 

 radiant energy, as not necessarily or obviousl}- 

 connected with ponderable matter, and mechanical 

 energy, which is always connected in some way 

 with material substance. All mechanical perfor- 

 mances in the plants depend on transformation of 

 some form of these, evident either as actual 

 energy doing mechanical work, or as energy of 

 potential ready to do work. 



In so far as molecular movements are concerned, 

 we have the special form of chemical energy. The 

 evolution of heat, light and electricity by plants 

 are instances of radiant energy, and so on. 



Many transformations of energy in the plants 

 are due to non-vital processes e.: transpiration. 



