On Trichophyton tonsurans {the Fungus of Ringworm). 245 



case the hairs were on the surface of the fluid, and in the other they 

 were completely immersed in it. 



It seems impossible to resist the conclusion from these and from 

 the earlier cell experiments that trichophyton cannot grow when im- 

 mersed in vitreous humour, whilst it grows freely when only moist- 

 ened by it. 



These experiments further suggest the view that inflammation cures 

 ringworm by drowning the fungus. The data supplied by recent 

 pathological researches show that serous effusion from the blood- 

 vessels is the invariable concomitant of inflammatory action, however 

 it is produced. When a persistent inflammatory congestion is kept up 

 by irritants around the hair follicles, it of necessity follows that the 

 serous effusion should make its way through the root-sheaths, whilst 

 the inner root-sheath, and the cuticle of the hair are more or less 

 broken up by the growth of the fungus. It is a fair inference 

 from the experiments described in this paper that the capacity 

 for growth in trichophyton must be destroyed by the resulting 

 immersion in serum. Clinically and as a matter of fact, we know 

 that this is just what takes place, and the only reason why ring- 

 worm is such a tedious disease under treatment is that the same 

 amount of irritation by external agents does not produce the same 

 amount of congestion in any two patients, and that a careful practi- 

 tioner will always hesitate to induce such an intensity of inflammation 

 as might injure the health of the patient or produce partial baldness 

 by destruction of the hair follicles. Trichophyton tonsurans, although 

 it grows in the epidermis of children and adults alike, and thrives in 

 the hairs of the scalp in children, cannot, as a rule to which there is 

 hardly any exception, live in the hairs and follicles of the scalp of 

 adults. The explanation of this peculiarity will probably be found in 

 the anatomical relations of the inner root-sheath and the hair, and I 

 suggest as an hypothesis that the fungus does not penetrate between 

 these structures in the adult because it does not find there sufficient 

 moisture for its development. 



Preparations showing the mycelium well, with the process of spore 

 formation as it takes place within the hair- shaft, do not appear to 

 haYe been often portrayed, if we may judge by the figures in ordinary 

 medical works, most of the drawings which are found in text-books 

 of medicine representing it imperfectly. 



I found that hairs which had been macerated for several days in 

 vitreous humour afforded excellent specimens for observation. 



Good preparations of trichophyton, showing the different stages of 

 development, are easily obtained by ordinary methods from scrapings 

 of the epidermis in ringworm of the skin of the body, and an excellent 

 representation of the appearances then seen is given in Cornil and 

 Eanvier's "Manuel d'Histologie Pathologique," p. 1221. 



