140 SOUTH AFRICAN BOTANY 
microscope. The bright globules of oil can be seen 
clearly, and if a solution of potash is added and the 
sections gently warmed these globules will become 
cloudy and dissolve. In the cells of the Sunflower 
cotyledons, rounded grains can be seen ag well as the 
oil globules. If the section is stained with iodine solu- 
tion, these grains stain brown or yellow, showing that 
they are aleurone grains. 
111. Experiment 17.—Cut sections of the cotyledons: 
of the Bean seed, mount in water, and stain with 
iodine. The grains in the cells all stain purple, show- 
ing that they are starch. 
Cullulose stains blue with Schultz’s solution. Sugar 
will give a red precipitate if a few drops of Fehling’s 
solution are added and the liquid heated. ‘Inulin is pre- 
cipitated by alcohol in the form of, very characteristic 
crystals, called sphaerites, marked by a series of con- 
centric and radiating lines. 
112. Ferments are substances found in plants and 
animals, which have the power of inducing chemical 
changes without themselves being changed. 
Diastase, which changes starch into sugar, has already 
been mentioned, and there are others which act upon 
proteids, oil, cellulose, etc., and convert them into simpler 
substances. By means of these ferments, the various 
insoluble storage materials are converted into forms in 
which they can diffuse through the organism. 
113. Respiration or breathing takes place in plants 
just as it does in animals. Every living thing requires 
a supply of energy, and this is obtained by respiration. 
In a machine, fuel is burnt and thus energy is replaced 
