Contractions. - Crotal. Crt.

Class, Reptilia; Section, Squamata; Order, Ophidia; Sub-order, Viperinae; Family, Crotalidae; Genus, Cro-talus; Species, Horridus, Durissus.

Rattlesnake.

Habitat. - America.

Part employed. - Venom.

Characters of Venom, Pure. - A clear greenish orange, viscid fluid; sp. gr. about 1035; of acid reaction; φ, clear, viscid, pale yellow. Both are miscible in all proportions with water; but alcohol causes a heavy flocculent precipitate. This precipitate is the active principle - Crotaline.

Characters of Crotaline. - A pale yellow, amorphous powder, neutral; soluble in water, insoluble in alcohol.

Characters of Genus. - 4 to 6 feet long, gradually swelling towards the middle, where it is 5 to 8 inches in circumference; back and sides covered with keeled scales; belly with unkeeled plates, which are always single under the tail. Head broad and triangular, with a large pit on each side below and in front of the eye; fangs half to one inch long; tail terminating in a rattle. Ground colour of back varies from yellowish-tawny to blackish-brown; of belly, from whitish-yellow to brownish-grey. A central and two lateral rows of dark spots along the back, confluent on posterior half of body. Tail generally black.

Collection. - The venom of this deadly serpent is procured by pressing the gland whilst the serpent is either pinioned in a frame or narcotized by Chloroform, and, as the venom drops from the fang, receiving it in a small graduated phial and immediately preserving it in pure Glycerine - 1 part venom and 9 of Glycerine. This is called φ, as the strongest officinal preparation. (Vide p. 32.) Glycerine is the best menstruum for preserving it; strong alcohol precipitates its active principle, and being an animal substance, it will not keep in trituration.

This powerful drug has been very thoroughly proved, and the symptoms, elicited and collected by Drs. Hering, Mure, and others, have been arranged in a schema in the "Hahnemann Materia Medica."

Preparation. - For the lx attenuation, we use pure Glycerine; for the first 5 centesimal, a mixture of 1 part Glycerine and 3 parts proof spirit; and for the 6th and upwards, spirit 20 O.P.

Reference to Horn. Proving. - Wirkung d. Schl., Hahn. Mat. Med., Mure's Mat. Med.

Dr. Hayward, of Liverpool, who has been for some time conducting experiments with Crotalus, has kindly supplied much of the foregoing information.

Proper forms for dispensing. - Below 6, Tincture only. 6 and upwards, Tincture, Pilules, or Globules.