This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
Trichophytosis is a contagious phyto-parasitic affection, characterized by the development of circular patches, commonly known as ringworm, on various parts of the surface of the body. These patches increase centrifugally, and are accompanied with profound alterations of the hair on the affected parts.
Trichophytosis depends on the lodgment and growth of a parasitic fungus called the Trichophyton Tonsurans, the discovery of which is due to M. Gruby, in 1842.
The fungus itself consists of spores and mycelial tubes. The spores are mostly round and much smaller than those of the Achorion Schon-leinii described in connection with Favus, and the mycelium is usually not so abundant. The favorite, if not exclusive, seat of the parasitic growth is in the hairs and hair-follicles. After it has gained a lodgment in the follicle, it almost immediately invades the hair-root, infiltrating it abundantly among and between the longitudinal fibres of the hair. This infiltration proceeds in an outward direction, until it has extended a short distance (one-sixteenth to one-eighth of an inch) beyond the surface of the skin. The spores separate the fine fibres of the hair, and by pressure force them apart. The portion of hair just without the follicle, and no longer possessing the support of the follicular walls, yields to the rupturing force of the parasite and breaks off, leaving a ragged and brush-like extremity protruding from the follicle. If a hair be extracted and examined under the microscope, it will exhibit the appearances shown in the annexed cut, Fig. 31.
* Op. cit. See note to p. 61 of this book.
By the aid of these spores the disease is conveyed from one to another under circumstances that will be noted later. The disease is met with in some of the lower animals, and may be conveyed from them to man.
There are four principal varieties of Trichophytosis founded on the different appearances and course presented by the disease according to the locality which is invaded by it. These varieties are known as Trichophytosis capitis, Trichophytosis barbae, Trichophytosis corporis, and Trichophytosis genito-crunlis. As the varieties differ in many essential respects both as to appearance, course, and appropriate treatment, they will be separately described.
Fig. 31. - Portion of a hair infiltrated with the spores of the trichophyton tonsurans.