PLAN't PHYSIOLOGY 139 
Test it with a glowing splint; this immediately bursts 
into flame, showing that the gas is oxygen. 
Deduction.—Green water plants give off oxygen in 
the sunlight. 
108. Storage of Reserve Material.— Most of the starch 
formed in the leaves by the process of assimilation is 
used up by the plant in the processes of respiration and 
growth, but some is stored up in various parts of the 
plant as reserve material. Starch, being insoluble in 
water, is acted upon by a ferment called diastase, which 
transforms it into sugar, and in this form it is conveyed 
to other parts of the plant. 
109. Reserve Materials.—These are found in various 
parts of the plant, in seeds, underground stems, roots, 
leaves, and fruits. There are various storage forms of 
food material. Carbohydrates are substances which 
consist of Carbon, Hydrogen and Oxygen, and starch 
and cellulose are the two chief forms in which carbo- 
hydrate is stored up. Starch is found in the cotyledons 
of the Bean, and in the endosperm of the Mealie, while 
the cell-walls of the endosperm tissue of the Date seed 
are thickered and represent storage of carbohydrate 
in the form of cellulose. Other forms of carbohydrate 
are inulin (found in the roots of many Compositae) and 
sugar (found in the roots of Carrot and Beet, and in 
the fleshy leaves of the Onion bulb). Oil forms the 
storage product in many seeds, e.g. Castor-oil, and in 
others we find aleurone grains, e.g. Sunflower. 
110. Experiment 16.—Cut thin sections of the coty- 
ledons of Sunflower, and of the endosperm of Castor- 
oil seed. Mount in water, and examine under the 
