VEGETABLE CYTOLOGY 
S 3 
are mostly colorless and crystallizable. They can be precipitated 
by one or more of the following alkaloidal reagents: tannic acid, 
gold chloride, phospho-molybdic acid, picric acid and potassio- 
mercuric iodide. 
Examples of Alkaloids 
Strychnine. — This alkaloid, with a chemical formula of C21H22N2- 
O2, occurs in the seeds of Strychnos nux vomica, Strychnos Ignatii 
and other species of Strychnos. When sections of strychnine con- 
taining seeds, previously treated with petroleum ether and absolute 
alcohol, are mounted in a solution of 1 Gm. ammonium vanadate 
in 100 mils of sulphuric acid, they take on a violet-red color which 
later changes to brown. 
Veratrine. — This alkaloid, with a composition of C37H53NO11, is 
found in various parenchyma cells of Veratrum album. If sections 
of the rhizome or roots are mounted in 2 drops of water and a drop 
of concentrated H2SO4 and examined microscopically on a glass 
slide, the cell contents and walls of the cells which contain this sub- 
stance first take a yellow color which soon changes to an orange-red 
and then to a violet. 
Nicotine. — This is a volatile alkaloid having the formula of 
C10H14N2 which is found in the Nicotiana genus of the Nightshade 
family. Sections of tobacco leaves or stems mounted in dilute 
Lugol’s solution will show first a carmine-red color and then a red- 
dish-brown precipitate which in time loses its color. 
Caffeine. — This alkaloid, with a formula of C8H10N4O2 + H 2 0 , 
occurs in Thea, Coffea, Cola, Sterculea, Ilex and Neea. If thin sec- 
tions containing it are placed on a glass slide in 2 or 3 drops of con- 
centrated hydrochloric acid and gently heated and then 2 or 3 drops 
of gold chloride solution are added, the sections then pushed to the 
side and the liquid allowed to evaporate, slender yellowish branch- 
ing needles of caffeine gold chloride will be seen to separate. 
Cocaine.-^This narcotic alkaloid, having the formula C17H21NO4, 
is found in the leaves of Erythroxylon Coca and E. Truxillense. If 
sections of these leaves are prepared in the same manner as indicated 
for those containing Caffeine, but platinum chloride solution substi- 
