100 THE ART OF CULTURE. 



the spring, the fat has disappeared, but has not served as nourish- 

 ment. It has not caused the least increase in any part of their 

 body, neither has it changed the quality of any of their organs. 

 With nutrition, properly so called, the fat in these animals has 

 not the least connexion. 



The annual plants form and collect their future nourishment 

 in the same way as the perennial ; they store it in their seeds in 

 the form of vegetable albumen, starch and gum, which are used 

 by the germs for the formation of their leaves and first fibres of 

 the radicle. The proper nutrition of the plants, their increase 

 in size, begins after these organs are formed. 



Every germ and every bud of a perennial plant is the en- 

 grafted embryo of a new individual, while the nutriment accu- 

 mulated 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 functions of an organism, by furnishing to the 

 different parts the materials for the production of their peculiar 

 constituents. 



In animals, the blood is the source of the material of the mus- 

 cles and nerves ; by one of its component parts, the blood 

 supports the process of respiration, by others, the peculiar vital 

 functions ; every part of the body is supplied with nourishment 

 by the blood, 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. 



The smallest particles of sugar, when left to themselves, 

 crystallize, that is, they obey a power strictly chemical. It is 

 evident that starch and woody fibre are more highly organized 

 compounds than sugar, for they possess a form which they could 

 not have obtained by the mere power of cohesion. We may 

 suppose that starch and woody fibre were originally gum and 

 sugar, or that both have been formed from sugar ; but certain 

 conditions must be necessary for the conversion of sugar into 

 starch, so that it will not be affected when these conditions fail. 



