BOTANIC MATERIA MEDICA. 283 
in thin, amorphous, glistening scales of a pale- 
yellow color, or in yellow vesicular masses. 
Tannin is incompatible with all the vegetable 
alkaloid ; with salts of iron, lime water, acids and 
solutions of gelatineand albumen. Forms Tannin 
tannates with the alkaline salts, and insoluble pre- 
cipitates with animal compounds. Galls were 
known to Hippocrates, and fairly described by 
many of the Indo-Persian writers. Galls have 
been used as an antidote in the poisoning by al- 
kaloids. The officinal preparations are the 
tincture, ointment and powder. Dose of the 
tincture, 1 fluid drachm (4 grams); of the pow- 
der, 5 to1o grains. The ointment is principally 
used for its astringent effect. The tannin and 
gallic acid are now more generally used as rem- 
edies. Galls are imported from Smyrna and 
Aleppo, and are often known by these names. 
The best galls are those without holes and the 
variety known as the blue or green galls. 
Zea Mays, Maize, Indian Corn, Corn.— 
Natural order Graminacez. Native of the 
Americas, and now cultivated as a food in many 
of the Graminacez family, with its sessile-pis- 
tillate spikelets and its staminate flowers, which 
are arranged at the summit of the plant, throw- 
ing their pollen upon the pistillate spikes below, 
which are covered by abortive leaves or husks. 
The silk of the ear is but the elongated pistils,. 
one of which proceeds from each grain, kernel, 
or ovary. ‘The rachis is commonly known as 
the corn-cob, and the chaff which covers it, the 
