126 SMALL- pox IN SliKKP. 



ovinatioiis ; all these, however, have failed more or 

 less. The method of collecting it in capillary tubes, 

 and afterwards hermetically sealing them at the end, 

 is probably the best. Mr. Ceely has long been ac- 

 customed to preserve the vaccine lymph in this manner, 

 and speaks highly of it. Next to this plan, that of 

 charging ivory points, and allowing it to dry, is to be 

 recommended. How long the lymph will retain its 

 specific properties cannot be determined with accuracy : 

 l)robably it will be useless after being kept a few months. 

 Captain Carr speaks as if no difficulty existed in pre- 

 serving it ; but he does not say how this is to be done. 

 These are his words:— "where yearly inoculation is 

 practised, it is customary to reserve a stock of inocu- 

 lating materials fi'om one year to another*." On the 

 contrary, Mr. Youatt remarks, that " there is one dis- 

 advantage attending the use of the claveau [lymph], 

 that it retains its power not more than a few days, what- 

 ever care be taken of itf." These observations by 

 Mr. Youatt would lead to the inference, that the virus 

 becomes totally inert in a very short time, which how- 

 ever is not the case. 



The fresher the lymph, the more it is to be depended 

 on for ovination, as undoubtedly it is deteriorated by 

 age, and ultimately does become inert. Many of its 

 properties, however, depend on its original purity, and 

 creat care is therefore necessary in the choice of vesicles 

 from which to take it. Very large vesicles should not 

 be selected, as these in general are filled with little more 

 than ordinary serous exudations ; small ones, especially 



* Carr on Sheep-pox, p. 10. 

 t Youatt on Sheep, p. 544. 



