ON 



DEMODEX PHYLLOIDES, (CSOKOR,) 



IN THE SKIN OF CANADIAN SWINE. 



BY R. RAMSAY WRIGHT, M.A., B.Sc, 



Professor in University College, Toronto. 



In the American Naturalist for December, 1882, I announced the 

 discovery of this Demodex in pieces of pork-skin submitted to me 

 by Mr. R. Awde, Inspector of Food for the City of Toronto. The 

 portion of skin was thickly studded with white tubercles, varying in 

 size from a pin's head to a pea ; these did not project much above 

 the surface of the epidermis, but on reflecting the skin the larger ones 

 were seen to extend into the subcutaneous tissue. The tubercles are 

 enlarged sebaceous glands filled with hundreds of mites in various 

 stages of development. The parts of the body chiefly affected are 

 the mouth, cheeks, flanks, belly, and inner surfaces of the legs. 



Mr. Awde asserts that one in twenty of the pigs sent in to market 

 in Toronto during the pork season, are affected to a greater or less 

 extent with this cutaneous parasite. In view of such frequency it 

 is somewhat singular that its occurrence has not hitherto l - been 

 recorded elsewhere, except by Dr. J. Csokor, of the Veterinary 

 Institute at Vienna, Austria, who found in 1879, a herd of swine 

 from Galicia affected in this manner, and described the Demodex 

 causing the disease as a new variety, I), phylloides. 



The skin in these swine was, however, much more seriously 

 affected, the collections of mites in the glands having caused the 

 formation of subcutaneous abscesses frequently as large as a hazel- 

 nut, which in one or two cases had become confluent on the inner 

 surfaces of the legs. Mr. Awde has never observed any such cutane- 



1 After publishing the note in the American Naturalist, I learned that Dr. A. J. Johnson, of 

 this city, to whom Mr. Awde had submitted specimens of affected skin, had sometime ago 

 recognized the parasite as a Demodex, and mentioned the fact of its occurrence at the meeting 

 of the American Microscopical Society, 1881. 

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