PAKASITIC DISEASES OF THE SKIN. 255 



should be thoroughly cleaned out, and the woodwork gone ovor 

 with a solution of lime, or the ooze from the vat may be used in- 

 stead, so that the pens are thoroughly disinfected before return- 

 ing the sheep to them. Should this not be done, the dipping of 

 the' sheep is only palliative at the best, for as soon as the effects 

 of the dip leave the fleece the sheep will become re-infected 

 from their own surroundings. 



Lime and sulphur has not been recommended here as a dip 

 for general use, as, in order for it to be serviceable it has to be 

 properly made, requiring much experience to be able to mix it 

 so that the effects will not be deleterious to the fleece. The 

 presence of lime in the mixture tends to harden the wool fibres, 

 making them brittle and dry, appearing to rob the fleece of its 

 natural yelk. While experimenters on a few head of sheep at 

 agricultural colleges claim that its use does not set the sheep 

 back or interfere greatly with their well being, it has been the 

 experience of large feeders that hot lime and sulphur dips cause 

 great damage, in soiue cases blinding the animals, and in all 

 cases putting them off their feed for fourteen daj's or longer, 

 which does not seem to be the case where some of the standard 

 preparations have been used. 



Sheep li^ich/' (Melophagus Ovinua.) Ltnn. 



A v'ery common parasite of the sheep found generally 

 throughout the whole extent of the United States and Canada. 

 This parasite, while not nearly so destructive as that causing the 

 scab, produces sufficient damage to merit a study of its habits and 

 life-history. In appearance the sheep tick may be said to repre- 

 sent a greatly enlarged scab mite, with the exception of its being 

 minus suckers and feelers, and also only possesses six legs, 

 whereas the adult scab mite has eight. In length they are about 

 one-quarter of an inch, the body is short, broad, and tough. In 

 color it is ferruginous, its abdomen being a greyish brown, 



