358 VETERINARY BACTERIOLOGY 



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at about blood-heat. This dried virus retains its virulence for 

 several years, at least. The vaccine is prepared by mixing one part 

 of this material with two parts of water and placing in a hot-air 

 oven at a temperature of 95 to 99 for six hours. This dries the 

 material and attenuates the organism. It is then pulverized and 

 put up in packages containing a definite number of doses. Before 

 use, a cubic centimeter of water for each dose is added, and the 

 material mixed and then filtered. The injection then is made 

 with 1 c.c. The dried material, pressed into the form of tablets, 

 is sometimes inserted under the skin without suspending it in 

 water. Vaccination has proved quite satisfactory. 



Bacteriological Diagnosis. A presumptive determination of 

 the organisms may be made by smear preparations from the in- 

 fected tissues. Anaerobic cultures will demonstrate the specific 

 organism in pure culture if inoculated with a bit of the tissue 

 before decomposition has begun and putrefactive bacilli have 4 

 gained entrance. Animal inoculation, particularly subcutaneous 

 inoculation into the guinea-pig, may prove useful. Usually the 

 symptoms of the disease are so characteristic that a bacteriological 

 test is wholly unnecessary. 



Transmission. It is believed that B. chauvcei is widely dis- 

 tributed in nature. The disease occurs only in certain localities. 

 There are districts which are never affected. Attempts have been 

 made to correlate the topography of the country, such as character 

 of soil, presence of marsh land, etc., with the prevalence of the 

 disease, but without much success. Organisms closely related to 

 B. chauvcei may be found widely in the soil, but, for the most part, 

 they do not possess the peculiar pathogenic characters of this form. 

 Infection is believed to occur through wounds. The disease is 

 rarely, if ever, contracted directly by one animal from another. It 

 is a non-contagious infectious disease. It is not always possible to 

 locate the point at which the organisms gained entrance in fact, 

 these cryptic infections constitute a considerable proportion of the 

 rases. It is possible that the explanation sometimes offered for 

 similar infections in tetanus will hold good here also; that is, that 

 the organisms may occasionally gain entrance to the blood from the 

 intestinal tract, and that they cannot produce disease except when 

 they lodge in some tissue that has been injured, as from a bruise. 



