QUARTER-EVIL. 219 



increasing numbers in the blood of the heart and in the internal 

 organs. 



Quarter-evil and malignant oedema, though possessing points of 

 resemblance, are distinct diseases. Not only do the bacilh in the 

 two cases differ in minute morphological and biological details, but 

 Eatasato showed that guinea-pigs rendered immune against virulent 

 quarter-evil had no immunity against malignant oedema. 



Protective Inoculation — Arloing, Oomevin and Thomas have 

 produced immunity by inoculating healthy cattle with a small 

 quantity of the fluid from the tumour of an infected animal. 

 Eeoovery takes place, and subsequent inoculation with a strong dose 

 is without effect. Similar results may be obtained by intravenous 

 injection of a few drops of the exudation. For general application 

 of the system of protective inoculation, the virulent liquid and 

 afiFected muscles are dried at 32° to 35° C, and the dried mass 

 triturated with water and heated to 100° 0. This is used as the 

 first vaccine. 



An infusion similarly prepared, but only heated to 80° 0., forms 

 the second vaccine. The dxy powder is a convenient form for 

 general distribution, and ^-^ of a gramme is triturated with 5 cc. 

 of water, and ^ cc. is injected into each animal. In about ten days 

 the second vaccine is employed, and cattle so treated are said to 

 have a complete immunity from fatal doses. 



The place chosen for the injection is the under surface of the 

 tail, a short distance from the extremity. The hair is chpped at 

 this spot, and the point of a syringe is pushed in between the skin 

 and the bone, and the vaccine slowly injected. 



Eoux and Chamberland produced immunity by inoculation of 

 filtered cultures. Cultures in broth were deprived of bacilli by 

 heating to 115° C, or by filtration through porcelain. Guinea-pigs 

 were inoculated with three doses of 30 cc. at intervals of two days, 

 and subsequently injected with a solution of virulent black-leg 

 powder and lactic acid, which killed control animals in twenty-four 

 hours. Kitt employed cultures on agar a fortnight old, or fresh 

 cultures sterilised by steam for thirty minutes. It was found 

 possible to confer immunity in oxen, sheep, and guinea-pigs against 

 the most virulent extract. Kitt's method has the advantage over 

 others of only necessitating one single injection. Whether these 

 experiments are of scientific interest rather than of practical value 

 may be regarded as an open question. 



On the Continent, and especially in France, vaccination against 

 quarter-evil has been carried out extensively ; and by comparing the 



