504 YETERINAEY HYGIENE 



monia must be practised, and though there are some who 

 deny its value, and it is quite true that those countries 

 which have practised inoculation have not got rid of the 

 disease ; yet there is always one strong argument in its 

 favour, viz., that no system of inoculation can reproduce the 

 disease, and the same cannot be said for all methods of pro- 

 tective inoculation, notably rinderpest, anthrax, and black 

 quarter. 



Inoculation without the destruction of the affected, fails 

 to eradicate the disease, for the reason that some of the 

 animals which appear to have recovered from a spontaneous 

 attack are sources of infection for long after. It is true 

 they have got some degree of immunity, but they are 

 nevertheless spreaders of disease. 



The protective serum of pleuro-pneumonia is furnished 

 in abundance by a case of the disease. The pleuritic 

 effusion, collected while transparent and sweet, may be em- 

 ployed, mixed with glycerine as a preservative. Or the 

 serum may be collected from the lung tissue, though in our 

 experience this is a slow and not altogether satisfactory 

 proceeding, and even with the greatest care blood gets 

 mixed with it. 



Another way of obtaining serum is by the subcutaneous 

 inoculation of a calf, which produces a great swelling, and 

 from which the serum may be collected. 



The serum collected from the animal maintains its viru- 

 lence about twenty-five days, but if a protective material 

 be prepared from a pure cultivation of the microbe, the 

 virulence lasts for a considerable time. 



The method of inoculation is simple, the end of the tail 

 being selected and threads previously dipped in the virus 

 are introduced subcutaneously for about one inch and left 

 there for a few days ; or the material may be injected 

 with a hypodermic syringe, the dose being half a cubic 

 centimetre. 



The only untoward results of the operation are swelling of 

 the tail at its root, with great pelvic oedema, but such cases 

 ought to be recognised before the disease extends to the 



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