DISEASES OF SHEEP. 31 



drinking water, especially that in which flax has been 

 steeped ; spoiled fodder ; all- kinds of musty hay ; rotten 

 potatoes, carrots and other root-plants spoiled with mildew 

 and rust. It appears, however, that all these damaging in- 

 fluences do not immediately cause said disease; it often 

 happens that several of these circumstances combine their 

 effects upon a herd without causing any apparent disease ; 

 whereas it often appears under circumstances where none or 

 only a few of the above influences have been observed. 

 It is therefore possible that some unknown causes may pre- 

 vail ; for instance, the particular composition of the atmos- 

 phere in some localities, the topographical situation of the 

 country, the electrical influences of the air, sudden cold or 

 other unknown influences. It is also possible that several 

 of these causes may combine to produce disease. Up to 

 tlie present time nobody has succeeded in sufiiciently ex- 

 jjlaining this mystery. No age is protected against the dis- 

 ease ; it may happen to the tender lamb as well as to the 

 oldest sheep. Young sheep, however, are a great deal more 

 disposed to it than older sheep. The disease may occur 

 during all seasons of the year, in summer as well as in 

 winter, but generally occurs during the hot season, mostly 

 commencing in May, increasing during July, August and 

 September, and diminishing during the following months. 

 Sometimes it prevails during several years among a single 

 herd or within an entire district, increasing and diminishing 

 in its destruction or vehemence according to the tempera- 

 ture of the several seasons. The following special observa- 

 tions may further explain the subject : 



1. In the hot season, although some cases may occur in 

 winter, blood disease mostly prevails ; during the summer 

 the largest number of cases are observed during July, Au- 

 gust and September, especially during long-continued heat 

 and dryness, and particularly when the air is sultry or the 



