DISEASES DUE TO INTERNAL PARASITES. 207 



rinlay Dun prescribes for tapeworm as follows. 



Take. Oil of male shield fern 20 drops 



Oil of tvirpentine 30 drops 



Sulphuric ether 60 drops 



Beat all together with one egg and administer to the dog in 

 ; a small quantity of soup. This should be followed in twelve 

 ' hours' time by a dose of castor oil. This disease occurs more 

 frequently in lambs than in old sheep, presumably due to the 

 tissues of the young animal being softer and more easily pene- 

 trated by the parasites. As dogs are the most fruitful source of 

 distribution of this pest, and the sheep being the source from 

 which they obtain the same, it is advisable that all viscera and 

 heads from slaughtered sheep should be withheld from them, 

 unless thoroughly cooked. If this was imiversally carried out 

 the losses from gid would materially decrease. 



parasitic Nasal Catawb. 



This disease is directly attributable to the invasion of the 

 nasal cavities by a fly called the gad-fly (oestrus ovis), which de- 

 posits its larvae on the inside of the nostrils. The embryos 

 proceed to crawl up the nostrils, producing intense irritation of 

 the mucous membranes, investing the frontal and maxillary 

 sinuses. In appearance the gad-fly resembles an overgrown 

 house fly. When flying it is so quick as to be almost invisible. 

 It is a dull-colored insect, the head and thorax being about as 

 long as its abdomen, the back is brown, with small points and 

 patches of darker color, its under surface is dark brown, with 

 yellow spots at the center of each abdominal segment. The 

 wings are transparent, mottled with spots and stripes, they are 

 almost as long as the body, which they completely envelop. The 

 head is large, containing two large greenish eyes, the under sur- 

 face of the head has white markings. The antennae are short 



