TIMK TO TAKK LVMPM. 117 



ajiiainst a subsequent attack is thereby afforded to the 

 animal. 



Hurtrel D'Arboval says, that " on the third or 

 fourth day after the operation, sooner or later ac- 

 cording to the age and health of the animal and the 

 state of the weather, will the effects of the inoculation 

 become apparent ; but if no signs are manifested by 

 the eighth day, it is a proof that the inoculation has 

 failed, and must therefore be repeated*." We can 

 bear testimony to the correctness of these statements, 

 for, as our experiments will shew, the specific inflam- 

 mation has appeared sometimes on the third day of 

 ovination, while in one instance it did not come on till 

 the seventh day (see page 110). And we have often 

 been obliged to re-inoculate an animal to secure sue- 

 cess, in consequence of its system being insusceptible 

 to the action of the variolous poison when it was 

 previously introduced. The same fact is spoken of by 

 Captain Carr, who uses the following words : " As, 

 however, even with the utmost care, many animals do 

 not take the infection by the first inoculation, it is re- 

 quisite to examine the whole flock after the lapse of 

 six or seven days fi-om the date of the first operation, 

 and to inoculate a second time wherever the first has 

 proved abortivef ." 



The period at which lymph can be collected from 

 the eruptive vesicles of either the natural or inoculated 

 pox, will necessarily be regidated by the duration of its 

 incubative stage. It is very seldom that the vesicles 

 are sufficiently matured to yield lymph before the 



* Art. Clavelization. 

 t Sheep -pox, p. 12. 



