52 DISEASES OF SHEEP." 



sheep pox, but of a very gentle and innoxious nature, by 

 which means the liability of the vaccinated animal to be- 

 come afflicted with the natural and more vehement or 

 malignant disease is destroyed. In other words, vaccina- 

 tion is the production of a mild disease as a safeguard 

 against a more vehement one. Vaccination is effected by 

 introducing a small quantity of pox-matter under the 

 epidermis of the animal by means of a small incision. 

 Vaccination was formerly vehemently opposed by many 

 persons on account of the unsatisfactory result of several 

 cases of vaccination ; which results were no doubt produced 

 by improper treatment and a combination of other un- 

 favorable circumstances. 



Like all other valuable and beneficial inventions, vac- 

 cination has had its trials and obstacles, until at last, suc- 

 cess crowning its own merits, and being more generally in- 

 troduced, certain rules in the manner of operation were 

 established according to experience ; so that at the present 

 time only a few opponents may be found, and those only 

 among ignorant or prejudiced people. The most important 

 advantages of vaccination are as follows : 



1. Natural pox generally destroys from twenty to fifty 

 per cent., and sometimes even a larger percentage, of an 

 infected herd, a destruction of only eight or ten per cent, 

 being a very rare and fortunate exception ; whereas the 

 destruction among vaccinated sheep very seldom exceeds 

 four or six per cent. ; in many cases there is a still smaller 

 loss, and sometimes no loss at all. I recollect a case in 

 which out of a herd of forty thousand vaccina,ted sheep 

 only ten animals died. 2. Natural pox generally prevails 

 in an infected herd from three to six months ; whereas a 

 vaccinated herd is relieved from pox in four or six weeks. 

 3. The amount of wool destroyed by the disease of infected 

 animals is a very considerable loss, no such loss occurring 



