62 
PHARMACEUTICAL BOTANY 
Etiolin is a pale yellow pigment which appears when green plants 
are kept for some time in darkness. It is probably identical with 
xanthophyll. 
Anthocyanins are applied to the blue, purple and red pigments 
which occur in the cell sap. The character of the color is claimed to 
be due to the alkalinity or acidity of the cell sap. 
Phycocyanin is the blue pigment found in the blue-green algae, 
associated with chlorophyll. It is soluble in water. 
Phycophaein is the brown pigment found in the brown algae. 
Phycoerythrin is the red pigment found in many of the red algae. 
The last two are always associated with chlorophyll but frequently 
conceal it. 
22. Latex. — This is an emulsion of varying composition and color 
found in special passages as latex cells and laticiferous vessels of 
many plants. It may contain starch, sugar, proteid, oil, enzymes, 
tannins, alkaloids, gum, resins, caoutchouc and mineral salts. The 
color may be absent as in Oleander; whitish as in Asclepias, Papaver, 
Hevea, and Apocynum; yellowish to orange as in Celandine, or red as 
in Sanguinaria. 
Chlor-zinc-iodine solution imparts to latex a wine red color. 
The latex of the following plants is of value to pharmacy and 
the arts: 
Papaver somniferum and its variety album which yields Opium. 
That from the unripe capsules is alone used for this drug. 
Palaquium Gutla which yields Gutta Percha. 
Hevea species, Ficus elaslica, Landolphia species, Castilloa elastica, 
Hancornia speciosa, Forsteronia species, Funlumia elastica and F. 
africana, Manihot species, Clitandra species and various species of 
Euphorbia furnish most of the Rubber of commerce. 
Lactuca virosa and other species of Lactuca yield the drug Lactu- 
carium. 
23. Enzymes. — An enzyme or ferment (according to Hepburn) 
is a soluble organic compound of biologic origin functioning as a 
thermolabile catalyst in solution. Ostwald has defined a catalyst 
as an agent which alters the rate of a reaction without itself entering 
into the final product, or which does not appear to take any imme- 
diate part in the reaction, remains unaltered at the end of the reac- 
