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MICROSCOPICAL AND NATURAL HISTORY SECTION. 

 November 6th, 1871. 



Joseph Baxendell, President of the Section, in the Chair. 



" On Tricophyton tonsurans," by Mr. John Barrow. 



Tricophyton tonsurans is the name now given to a 

 vegetable parasite which lives in and upon the skin of man 

 and some of the lower animals. 



For some months past this parasite has forced itself under 

 my attention, and I have been anxious to obtain the best 

 information concerning it, and, believing that the observa- 

 tions I have made may be of interest to the Section, I will 

 state what they are. 



Three forms of disease are known to which the popular, 

 or unpopular, name of ringworm is applied, viz. — ringworm 

 of the scalp, ringworm of the body, ringworm of the chin, 

 and another nearly allied, the liver spot. 



There appears little doubt that, of these three, the two 

 first are identical : but, as I have not had any opportunity 

 of observing any but the second — that of the body — I will 

 confine myself to that particular form. 



The first indication of the presence of this parasite was 

 on a child eight years old. A red ring appeared on the 

 face, about an inch in diameter, the edges being slightly 

 raised, and the centre rough and somewhat scaly. This was 

 declared to be ringworm, or herpes circinatus, by one 

 authority, and sulphurous acid was applied with success. 

 Very soon afterwards several patches appeared on the child's 

 bodyj varying from ^in. to 2in. diameter. Sulphurous acid 



