84 PHARMACEUTICAL BOTANY 
mounted in concentrated H,SO, will show a red coloration in the 
cells containing this substance. If water be added, a red powder 
is thrown down. 
Saponins are glucosides which have the property of frothing 
with water. They are found in Soap Bark, Senega, Saponaria, 
Yucca and other drugs and take a red color with strong H2SOu.. 
_ConIFERIN is a glucoside, occurring in the cell sap of the 
spruce, pine, and other plants of the Conifere. If sections con- 
taining it are first treated with a solution of phenol and then with 
sulfuric acid, the cells containing it take on a deep blue color. 
_Dierroxin, a glucoside found in the leaves of Digitalis pur- 
purea, is colored green with hydrochloric acid. 
CyANOGENETIC GLUCOSIDES are common in the seeds of the 
Rose and Legume families. They yield hydrocyanic acid when 
hydrolyzed by enzymes or other agents. 
7. PeNTostpEs.—These are substances related chemically 
to glucosides, differing from the latter in yielding pentose as one 
_of the products, when decomposed (hydrolyzed) by enzymes, 
dilute acids, etc. The aloins found in the juices of various 
species of Aloe are examples of these principles. One of these, 
“barbaloin,” found i in the official Aloe gives a greenish fluores- 
cence in aqueous solutions, when the latter are saturated with 
borax. 
8. ALKALoIps-—Chemically, these are basic carbonaceous 
amines which like glucosides are products of metabolism. Their 
method of formation in plants is uncertain. Some hold that 
they are katabolic products, resulting from the breaking down of 
tissues, while others believe them anabolic in character. They 
undoubtedly serve as defensive agents in plants containing them 
on account of their bitter taste and poisonous properties. 
PROPERTIES OF ALKALOIDS 
_Alkaloids are _invariably found in combination with acids 
forming. salts ; which dissolve in in water or “alcohol. They are 
composed of carbon, hydrogen and and nitrogen. Some contain 
oxygen. They are precipitated from saline solutions by the 
addition of alkalies. They are mostly colorless and crystallizable. 
They can be precipitated by one or more of the following alka- 
