al aid | 
THE FRUIT AND THE SEED 289 
general the natural carbohydrates contain six, or some multiple 
of six, carbon atoms. The simple carbohydrates have a sweet 
taste and are known as sugars. 
The forms of carbohydrates in which food is stored most abun- 
dantly are sugars and starches. Other forms are hemicellulose, or 
reserve cellulose, and inulin. 
Sugars. The three sugars 
that are found most abun- 
dantly in plants are glu- 
cose (grape sugar), fructose 
(fruit sugar), and swerose 
(cane sugar). Glucose and 
fructose have the formula 
C,H,,0,- They are thus com- 
posed of the same kinds of 
atoms in the same propor- 
tion, but the arrangement 
in the molecule is different. 
The simplest natural sugars 
have this formula and are 
known as monosaccharides. 
Sucrose (C,,H,,O,,) has twice 
as many carbon atoms and — 
is a disaccharide. It may be 
The cells contain large and conspicuous 
regarded cae osed of one erains of starch and small granules of 
molecule of glucose and one protein. (x 270) 
of fructose, which are linked 
together with the dropping out of one molecule of water. Su- 
erose is familiar as the ordinary granulated sugar of commerce, 
which is obtained from sugar cane or sugar beets. Maple 
sugar also is sucrose. Glucose and fructose are found in nearly 
all plants, and glucose is an ingredient of a thick sirup, which 
is made by treating starch with dilute sulphuric acid and 
afterward removing the acid. Such sirups are frequently called 
corn sirups, as cornstarch is most commonly used in their 

Fig. 290. Section of a few cells of mungo 
bean (Phaseolus radiatus) 
preparation. 
