CANTHARIS VESICATORIA. 



plaster ought not to remain on longer than is necessary to ef- 

 fect vesication, which takes place, generally, at the distance 

 of eight hours, even when the blister plaster has been re- 

 moved two hours before that time, and no vesication be then 

 present. 



Of late years, another insect has been introduced into 

 practice as a substitute for Cantharides, which appears to 

 possess all their vesicant and diuretic properties. This is a spe- 

 cies of the genus Mylabris, one species of which, the Mylabris 

 chicorii, is a native of the South of France, Italy, and Greece, 

 and known to the ancients. The genus Mylabris consists of 

 fifty-one species, of which twenty-eight are found in Africa. 

 The species employed as a substitute for Cantharides is the 

 Mylabris variabilis. It is brought from China, and is regard- 

 ed rather as a variety of the Mylabris chicorii than a distinct 

 species. M. Robiquet has analyzed it, and has found that it 

 affords cantharidin in as great abundance as the Cantharides. 

 It acts with as much energy as a vesicant as the best Cantha- 

 rides. Another species of Mylabris, the Mylabris pustulata of 

 Olivier, is also used as a vesicant in China. Some species 

 of Meloe, the Proscarabceus and Majalis in particular, also 

 contain cantharidin ; they may be used both as vesicants and 

 diuretics. If an easy method of obtaining cantharidin were 

 discovered, its use might supersede that of the entire insect. 

 The powder of Cantharides is now seldom used as an inter- 

 nal medicine, and the tincture, which is undoubtedly the best 

 preparation of the insect, is also the most generally employed. 



TINCTURA CANTHARIDIS. Tincture of Blister Beetles. Take 

 of blister beetles, bruised, an ounce ; diluted alcohol, two 

 pints. Macerate for fourteen days, express, and filter through 

 paper. 



The London College takes four drachms of the beetles, and 

 two pints (Imperial measure) of proof spirit, macerates for seven 

 days, expresses, and filters. The Dublin, half an ounce (avoir- 

 dupois) of the former, and two pints (Imperial measure) of the 

 latter, and macerates for two weeks, strains, expresses, and fil- 

 ters. The Edinburgh College takes the same proportions as 

 the London, digests for seven days, strains, expresses the re- 

 siduum strongly, and filters ; or prepares the tincture by per- 

 colation, having previously moistened the coarsely powdered 

 beetles with a little of the spirit, and allowed them to stand 

 for twelve hours. 



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