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20 ESSENTIALS OF BOTANY 
25. Chemical Tests for Proteids. — All proteids (and very 
few other substances) are turned yellow by nitric acid, and 
this yellow color becomes deeper or even orange when the 
yellowish substance is moistened with ammonia. They 
are also turned yellow by iodine solution. 
EXPERIMENT VII 
Detection of Proteids in Seeds. —Extract the germs from some 
soaked kernels of corn and bruise them ; soak some wheat-germ meal 
for a few hours in warm water, or wash the starch out of wheat-flour 
dough; reserving the latter for use, place it in a white saucer or por- 
celain evaporating dish and moisten well with nitric acid; examine 
after fifteen minutes. 
26. The Brazil-Nut as a Typical Oily Seed. — Not many 
familiar seeds are as oily as the Brazil-nut. Its large size 
makes it convenient for examination, and the fact that this 
nut is good for human food makes it the more interesting 
to investigate the kinds of plant-food which it contains. 
EXPERIMENT VIII 
Testing Brazil-Nuts for Plant-Foods.— Crack fifteen or twenty 
Brazil-nuts, peel off the brown coating from the kernel of each, and 
then grind the kernels to a pulp ina mortar. Shake up this pulp 
with ether, pour upon a paper filter, and wash with ether until the 
washings when evaporated are nearly free from oil. The funnel 
containing the filter should be kept covered as much as possible 
until the washing is finished. Evaporate the filtrate to procure the 
oil, which may afterwards be kept in a glass-stoppered bottle. Dry 
the powder which remains on the filter and keep it in a wide- 
mouthed bottle. Test portions of this powder for proteids’and for 
starch. Explain the results obtained. 
