" braxy " sheep disease in australia. 585 



Immunization by Feeding with Virulent Cultures. 



Hamilton recommended the administration of virulent cultures 

 per oram to sheep during his so-called " immune season " as a means of 

 producing an active immunity to British braxy during the danger 

 period of the year, and actually drenched with such cultures the 

 flocks on several farms, the results of which he considered highly 

 satisfactory, but I understand this method of prevention has been 

 entirely discontinued for several years in Scotland. 



Now, although we have not been able to demonstrate any 

 seasonal period of immunity to the experimental production of the 

 disease here, and sheep have been tested each month, yet we have 

 been able to demonstrate that a definite immunity may readily be 

 established by the simple process of administering virulent cultures 

 per oram. 



A sheep (27) was drenched with 2 cc. virulent Tasmanian 

 culture mixed with an ounce of milk, and sheep 29 of the same age 

 was similarly drenched with 2 cc. virulent Victorian culture. A 

 month later sheep 27 was inoculated with 0.25 cc. virulent blackleg 

 culture, to which it succumbed thirty-seven days after drenching. 

 Sheep 29 was inoculated with 0.25 cc. virulent Victorian braxy 

 culture, to which it proved immune. Nineteen days later it was 

 inoculated with 0.25 cc. virulent Tasmanian culture, to which it 

 also proved immune. 



Two nine-months old lambs (34 and 35) were dosed with 1 cc. 

 each of virulent Tasmanian culture in the following manner : — The 

 culture, mixed with gelatine, in which was a considerable quantity 

 of roughly ground glass, was placed in a gelatine capsule, so as tO' 

 make a " bolus," and this was administered in the usual way. 



The experiment was conducted in the anticipation that some 

 portions of the ground glass contaminated with the bacteria would 

 pierce the mucosa of some part of the alimentary tract, thereby 

 producing the disease and so demonstrating as fairly as possible 

 the presumed role of prickles, parasites, etc., in the natural produc- 

 tion of the disease. The animals, however, remained perfectly 

 normal. 



A month after lamb 34 was drenched it was inoculated with 

 0.25 cc. virulent Victorian culture. Of the same culture and from 

 the same' syringe sheep 29 received 0.5 cc. (a month after the 

 previous inoculation), and lamb 33 (same age and breed as 34) 

 received as control 0.25 cc. The result was that 29 and 34 remained 

 practically normal, but for a slight and passing rise of temperature, 

 whereas lamb 33 was dead in 18 hours. 



Lamb 35, six weeks after drenching, was inoculated with 0.25 

 cc. virulent Tasmanian culture (0.01 cc. being fatal for an adult 

 guineapig in less than 20 hours). For two days the animal re- 

 mained normal, then a slight lameness with a faint swelling of the 

 inoculated thigh was observed, the temperature being 103.5. Gradu- 

 ally the lameness and swelling increased, thoughslowly, and the animal 

 died five and a half days after inoculation. This indicated a great 



