1 8 MANURES FOR FRUIT TREES 



to the famous Malpighi is due the fact that the 

 leaves elaborate the crude sap, which passes from 

 the roots to the leaves by the fibrous elements of 

 the wood. Equally important were the experi- 

 ments of Mariotte, which proved that diflferent 

 plants drew the same ingredients from the soil, but 

 make diflferent materials out of it. 



In concluding this short chapter on the functions, 

 etc., of plant life, it may be remarked that the 

 elements of the living plant have further the 

 chemical peculiarity of forming with each other 

 most numerous combinations, and very large 

 molecules. How the plant forms the carbon 

 dioxide (respiration), which it evolves, is unknown, 

 and yet there is no life without the formation of 

 carbon dioxide ! The reason why this problem 

 has not been solved, lies doubtless in our in- 

 suflficient knowledge of the nature of the place 

 where the formation of carbon dioxide takes place. 

 That the foci of oxidation lie exclusively in the 

 protoplasm is certain, but what is their aspect ? 



