The preventive measures directed against black-quarter and an investigation into the efficacy of setoning / by Stewart Stockman.

Date:
[1897]
Catalogue details

Licence: Public Domain Mark

Credit: The preventive measures directed against black-quarter and an investigation into the efficacy of setoning / by Stewart Stockman. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    their existence in the blood-steam, we have the occurrence of tumours away from the seat of inoculation and the presence of bacilli in the cavities. On aprio7'i grounds, then, natural infection seems to operate by ingestion of spore-contaminated material, or by the spore gaining access to the subcutaneous tissues through a wound. I incline to think that the latter method is the more common, because the disease is relatively rare in coated animals like the sheep, although it is the most susceptible of all to inoculation. Infection does not operate equally well in every part of the body. We seldom get evidence of the virus having penetrated by those parts where the connective tissue is dense, and it has been shown experimentally that it is more difficult to obtain positive results by inoculating at parts such as the tail or the ear. In the practice of preventive inoculation advantage has been taken of this observation. Fewer animals die from the inoculation when performed at the extremity of the tail. However, this method has its disadvantages. Accidents similar to those which followed preventive inoculation against pleuro-pneumonia are said to be fairly frequent. Moreover, it is not easy to insert a needle at this part, both on account of the movements of the animal and the density of the tissues. The other parts where the operation is practised are behind or in front of the shoulder. Methods of Preparing the Vaccine {^Arloing, Cornevin and Thomas'). The black-quarter virus in the dried state is very resistant to the action of heat. A dry temperature of i io° C. continued for six hours is necc.ssary to completely destroy it. The same temperature when got by superheated steam destroys it in twenty minutes. Arloing, Cornevin, and Thomas say that the dry virus must be exposed to a dry temperature of 85° C. for si.x hours to obtain a solid diminution of virulence. Between these ranges of temperature one can obtain virus of vary- ing strength. To obtain their vaccine they proceed as follows. A portion of the affected muscle is bruised in a mortar with a few drops of water. The liquid containing the virus is filtered through muslin. It is then spread in a thin layer on a plate and dried at 37° C. After drying, one scrapes the plate and obtains reddish-brown scales or powder. This virus remains active for a long time. To attenuate its virulence one adds two parts of water to one of powder. The mixture is spread out on a plate in a thin layer, and exposed to a dry temperature of from 100-104° C. for seven hours. A brownish scaly material is afterwards scraped off the plate, and this is the first vaccine. A second and stronger vaccine is obtained by exposing the virus similarly prepared to a temperature of from 9^-95 C. for seven hours. The only agent that can possibly resist this temperature is the spore, but it becomes attenuated. The reddish material is powdered finely and sent out in packets. Before use, one puts the powder in a sterilised mortar (boiled fifteen minutes), and adds sterilised water (boiled) to the amount of 10 cc. The mixture is then filtered through muslin which has been previously boiled. Arloing, Cornevin, and Thomas advise the inoculation to be