5 



distance to which this work of bud-growth extends, varies 



4 



greatly within and outside of the species, and is not a matter 

 to concern us farther at the time. 



RESERVE FOOD-MATERIALS. 



Plants which live from year to year do not use up all the 

 nourishment prepared by the green parts, principally the 



* 



leaves, during the season of active growth. They lay by a 

 portion of this material to be employed in the vital processes 

 at times when the plant cannot assimilate the crude sub- 

 stances which are obtained from the soil and the air. In short, 

 perennial plants, during the growing season, store some of 

 their elaborated substances in places where it becomes availa- 

 ble for nutrition in the early spring, whil-e the plant is putting 

 forth its young twigs and leaves. This reserve material, as it 

 IS termed, may for convenience be divided into two groups: 

 namely, those which are known as carbohydrates; so called 

 because consisting of carbon and the elements of water, that 

 is, of carbon, hydrogen and oxygen, united in definite propor- 

 tions. The leading carbohydrate is starch, familiar to every 

 one as the basis of many foods for animals and man, as found 

 in potatoes, corn, and a long list of other vegetable products. 

 Oil is another reserve form assumed by the carbohydrates, 

 and abounds in mdny seeds and other parts of plants. Sugars, 

 which by themselves make up a group of the carbohydrates, 

 are often found associated with the other forms of reserve 

 food-material above mentioned. There are other forms of 



carbohydrates, but they do not specially interest us in this 

 paper. 



The second division of reserve material, suitable for plant 

 nutrition, is known as albuminoids, so named from a resem- 

 blance to the albumen or white of ece. Protein is another 

 term given to the same group of substances, all members of 

 which agree in having nitrogen in their composition^a sub- 

 stance which is absent in the carbohydrates. They are more 

 complex and less stable compounds than the carbohydrates, 

 and are stored usually as amorphous contents of cells. Some- 

 times, however, they assume the form of grains (aleurone), or 

 crystal-like bodies (crystalloids), and in these condensed condi- 

 tions may be met with in seed, like beans and peas, which arc 



