66 DISEASES OF SHEEP. 



a regular course or progress, and where the animals do not 

 suffer from vehement inflammation or general bodily afflic- 

 tion. If vaccine-matter is transferred from sheep suffering 

 from pox together with chlorosis, or so-called green sick- 

 ness or rot, the effect of such matter is destroyed; the vac- 

 cination results only in the formation of a sore, which ren- 

 ders no protection and no formation of further useful vac- 

 cine-matter. It has been also ascertained that other diseases 

 of sheep cannot be transferred or propagated by vaccination 

 with matter obtained from such otherwise diseased animals. 

 Suppurated matter or blood obtained from overripe pox de- 

 stroys the intended effect of vaccination, and in some 

 cases natural pox is the result of such improper treatment 

 (from which result ignorant peojDle are inclined to believe 

 that vaccination is always a failure). It is further preferable 

 to obtain vaccine-matter from vaccinated sheep ; and in case 

 no such matter can be had, it should be obtained from in- 

 fected animals whose pox is of a regular and of the least 

 vehement nature. Natural pox are smaller than vaccinated 

 pox, and consequently only a small quantity of lymph can 

 be obtained from the former ; for this reason the blood from 

 natural pox during its proper maturity must be used. 

 Lymph may be preserved for a considerable time without 

 losing anything from its effects ; for this purpose it should 

 be collected in very small vials, or so-called capillary tubes, 

 which must be carefully corked and sealed up with cement 

 or wax, and kept in a jar filled with sand, and in a cool 

 place. In this way the lymph may be preserved from four 

 to ten months. Another means of preserving vaccine- 

 matter consists in collecting it by means of wool or cotton, 

 to be carefully sealed up in glass vessels. There are, how- 

 ever, certain exceptions recorded, in which the most care- 

 fully preserved vaccine-matter has, after a short time, lost 

 its effective power. The preservation of lymph having in 



