34 
which results in the formation of starch or sugars. Our com- 
mercial sources of starch are the storage organs of plants such 
as seeds, thickened fleshy stems and roots and even the pith o 
woody trunks. Agricultural plants can be roughly classed as 
those which store starch, such as the cereal grains, corn, rice, 
the potato, etc., and those which store sugar, such as sugar cane, 
the sugar beet, sorghum, etc. Starches are more commonly 
stored by the plant for use in its own future growth periods. 
Sugars may serve in the same way, but also are not infrequently 
found associated with other attractively flavored food elements 
in fruits, nectaries, etc., where they serve as baits to attract 
insects and other animals whose agency is needed for cross 
fertilizing. aed seeds, etc. It is a aga that 
over half of all our foods have a sweetish taste. The number of 
sugars is very great and their food values vary within acre limits. 
The chemistry of the starches is less well understood but their 
general properties vary to a considerable degree according to the 
type of plant from which they are obtained. 
Chemically considered the starches and sugars are types of the 
great group of the carbohydrates. The chemical characteristics 
of the carbohydrates are largely deeanined by the qualities of 
the element carbon and Van't Hoff was willing to assert that life 
itself is but the vast and complex expression of the chemical 
properties of carbon compounds,—under the present temperature 
conditions of the earth. Such a statement is to be taken as the 
plants and animals the carbohydrates are transported and 
taken up in growth processes in the form of sugar, starch repre- 
senting a compact storage substance which appears in the plant 
tissues when there is an excess of food, much as fat is produced 
in the animal tissues. So far as known a remarkable similarity 
has been found between ee processes by which starches are 
converted into sugars and thus utilized in both plants and 
animals. The digestive juices of a seedling are quite comparable 
to those of an animal and plant enzymes may be used as a sub- 
stitute by the animal in case of a deficiency. 
