364 ON THE SHEEP OF ZETLAND. 



heads all incline towards the centre. By this ar- 

 rangement, their breath keeps them warm, and 

 dissolving part of their icy covering, forms a kind 

 of vault above their heads. In this situation, 

 they have been known to remain for many days, 

 during which they appear to maintain life, by 

 eating the wool from off each other's backs. 



Such a mode of managing the sheep, no doubt 

 renders them obnoxious to many diseases, and it 

 is certainly an ungrateful return to those who so 

 often have 



—given us milk in luscious streams^ 

 And lent us their own coat against the winter's cold. 



Yet, except in seasons when the weather is un- 

 usually bad, and the food scanty, they may be 

 said to be comparatively healthy ; and the most 

 severe and fatal distempers with which they are 

 afflicted, have been imported into the country, 

 within a period of forty years. 



Blindness first made its appearance among the 

 Zetland sheep, in 1770, and it was traced to 

 communication with a ram from Montrose, which 

 laboured under the disease at the time he was 

 brought to the country. This affection consists 

 in the formation of a film over the whole anterior 

 part of the cornea, which produces complete 

 blindness. When the attack is not very violent, 

 it wears off in about a fortnight, and it is observed 

 to disappear more readily, when the animal is left 

 to run at large, than when taken into a house * 



