NUTRITION AND GROWTH OF PLANTS. 127 



their increase in size, begins after these organs are 

 formed. 



Every germ and every bud of a perennial plant 

 is the engrafted embryo of a new individual, while 

 the nutriment accumulated in the stem and roots, 

 corresponds to the albumen of the seeds. 



Nutritive matters are, correctly speaking, those 

 substances which, when presented from without, 

 are capable of sustaining the life and all the func- 

 tions of an organism, by furnishing to the different 

 parts of plants the materials for the production of 

 their peculiar constituents. 



In animals, the blood is the source of the mate- 

 rial of the muscles and nerves ; by one of its com- 

 ponent parts, the blood supports the process of 

 respiration, by others, the peculiar vital functions ; 

 every part of the body is supplied with nourish- 

 ment by it, but its own production is a special 

 function, without which we could not conceive life 

 to continue. If we destroy the activity of the 

 organs which produce it, or if we inject the blood of 

 one animal into the veins of another, at all events, 

 if we carry this beyond certain limits, death is the 

 consequence. 



If we could introduce into a tree woody fibre in 

 state of solution, it would be the same thing as 

 placing a potato plant to vegetate in a paste of 

 starch. The office of the leaves is to form starch, 

 woody fibre, and sugar ; consequently, if we con- 



