TliEATMENT OF SHEEP-POX. 35 



tract of country, and extending to several counties ; whilst 

 enzootic relates to a circumscribed domain, and confined to a 

 small district, and spreading slowly. We recognise Variola 

 Ovijuc to be of the nature of a specific eruptive febrile disease. 

 It may be enzootic by being confined to a district, or even one 

 flock, while at the same time it may be epizootic by the diffusion 

 of its virulent principle, it being propagated slowly or rapidly 

 according to the inherent vitality of that virulent principle or 

 agent. Science has not yet clearly discovered in what manner 

 this particular virus is developed and propagated. We do know, 

 however, that this specific virulous agent has the power, under 

 certain circumstances, of multiplying itself and producing the 

 same series of a characteristic morbid phenomenon, and capable 

 of inducing a disease identical witli that which has produced it 

 in the same species. It is of a highly contagious constitution, 

 and can be easily conveyed from one flock to another in various 

 ways, and by the most simple media, such as dogs, &c. Shep- 

 herds readily convey it. 



There are several separate and distinct stages of develop- 

 ment. The latent or incubative is the first sta^-e ; it is tbn 

 period of implanting the disease and its development, or thai 

 of its rise and spread. This stage varies according to age, local 

 influences, feeding, condition of the blood, and the condition 

 of the sheep. During this stage the specific virulous agent 

 produces certain effects on the blood, various tissues begin to 

 swell, and the state of primary fever sets in. The flowing of 

 the saliva, also one of the effects, is at first abundant, but gradu- 

 ally and quickly subsides. The primary fever in a few days 

 generally remits and gives place to eruption, which may either 

 be distinct or confluent. When the eruption becomes confluent 

 the fever does not subside, but fluctuates in degree, and becomes 

 less regular. There is an aggravated form which sometimes 

 appears instead of suppuration, in which we have ecchymosis, 

 and, instead of vesicles, we have pustules and pedunculated 

 spots. When the malady is once developed its advance to other 

 stages cannot be averted by any remedial measures. It then 

 advances from one stage to another in the regularly^defined course 

 of the various stages of development, and after it has passed 

 through all the stages it may end in recovery or death. If it 

 should pass through all its ditl'ereut morbid phases and con- 

 valescence follow, then, as a rule, there is permanent immunity 

 from a second attack. The characteristic feature of this disease 

 is, that it originates through a virulent agent or specific blood- 

 poison, afid never arises spontaneously. If we were to entertain 

 the idea of spontaneous orij^in we then attempt to cover our 

 failure in tracing the relation of cause and effect by an im- 

 possible theory that it could exist without a cause. 



