STORAGE OF FOOD IN THE SEED - 93 
form in which it can be recognized under the microscope. 
One test for its presence is the peculiar smell which it 
produces in burning. Hair, wool, feathers, leather, and 
lean meat all produce a well-known sickening smell when 
scorched or burned, and the similarity of the proteid mate- 
rial in such seeds as the bean and pea to these substances 
is shown by the fact that scorching beans and similar 
seeds give off the familiar smell of burnt feathers. 
' 29. 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. Most 
proteids are turned more or less red by the solution of 
nitrate of mercury known as Millon’s reagent.} 
EXPERIMENT X 
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 
porcelain evaporating dish, and moisten well with Millon’s reagent 
or with nitric acid; examine after fifteen minutes. 
. 30. 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. 
1 See Handbook. 
