REVIEWS. 



41 



grows in the hair follicle, and is also found in abundance amongst the epithelium, 

 in the neighbourhood. It may be frequently seen within the hair in consider- 

 able quantities (fig. 8), and may be found in abundance in the little honeycomb- 

 like masses, termed favus crusts. 



Fig. 8. 



Fig. lu. 



" The favus consists of a little cavity, filled with spores of the fungus, granules, 

 and epithelial cells (fig. 9) ; one or two hairs usually pass through the centre 

 of the favus. The fungus is composed of the mycelium (a), or the proper sub- 

 stance of the plant ; of a receptacle (6), or sporangium, which contains the repro- 

 ductive organs ; and the reproductive organs them- 

 selves, or the spores. 



*' This fungus occurs in Tinea favosa, Porrigo 

 favosa, scutulata, &c. The favus may be placed 

 upon a glass slide, moistened with water, and 

 subjected to microscopical examination. When 

 the hair is to be examined, the same course is 

 pursued ; but it will often be found advantageous 

 to treat it with a drop of the solution of potash, 

 which renders the hair more transparent and the 

 fungus more distinct. 



" There are several other species of fungi infest- 

 ing the hair ; the Tricophyton tonsurans is found in 

 the form of very minute, oval or rounded, per- 

 fectly transparent cells, within the bulb, and in 

 the central canal of the hair. When it occurs 

 external to the canal of the hair, its presence de- 

 pends upon the hair having been broken, and 

 the escape of the contents. 



u Other species are found in the epithelium of the skin. That condition of the 

 skin termed Pityriasis versicolor, depends upon the epithelial cells in the coloured 

 situations being infested with spores of another of these minute fungi. Cases havo 

 occurred in which a previously healthy individual has been infected with the disease 

 after having slept with a patient suffering from this affection. 



" Parasitic plants are met with in the following skin diseases : 



1. Tinea tondens. 



2. Tinea iavosa. 



3. Mentagra. 



4. Pityriasis versirolor. 



5. Porrigo decalvuns. 

 0. Plica polonica. 



VOL. II. 



