536 



DISEASES OF THE SKIN, 



also been called lichen. It is due to a vegetable parasite, Tricho- 

 phyton tonsurans. This fungi, which belongs to the group of Muce- 

 dines, was discovered by Gruby in 1842, and studied by Malmsten 

 in 1845. Gerlach has demonstrated that it is the agent of the de- 

 pilating thrush of our animals; in 1857 he published a work on this 

 disease which is still classical. Contagion operates through grooming 

 utensils, harnesses, blankets, and by direct contact (suckling). It 

 may also occur on pastures where the animals are frequently in im- 

 mediate contact. Breeding animals of the male sex may communicate 

 the disease to all subjects of their species which cohabit with them. 



It exists ordinarily among animals of the bovine species without 

 any distinction as to age ; the dog, horse, goat, and cat follow in 

 order ; sheep and pigs are rarely affected ; it may be transmitted to 

 the rabbit by inoculation. In general, however, it is quite a rare 

 disease, and one which does not exist everywhere ; it seems to be 

 stationary on certain premises, and exists permanently in several 

 countries (England, Holland, France, Switzerland), where it is 

 much more common than elsewhere. 



Its transmission to man has been mentioned by numerous authors ; 

 persons affected by it are generally those working in stables, or who 

 take care of sick animals, or have been engaged in skinning animals 

 affected by thrush, which have been killed for consumption. The 

 dog may communicate it to man by its caresses (Friedberger). In 

 the human species it assumes, at times, an endemic character. In 

 1840 almost all the inhabitants of a Swiss village (Andelfingen) 

 were contaminated by diseased oxen. In Berlin cases of tranmis- 

 sion of thrush of the dog to man are frequent ; in 1887 we observed 

 and treated at the polyclinic of the veterinary school a score of cases 

 of human favus of canine origin. We have observed it several 

 times in all the members of one family. 



Morphology and physiology of Trichophyton tonsu- 

 rans. Microscopic examination of the Tricophyton tonsurans per- 

 mits us to recognize two kinds of elements in it : filaments and 

 spores. 



1. Filaments or mycelia are very fragile elongated tubes, of a 

 thickness of 4 they are straight or undulated, simple or articu- 

 lated, ramified according to the dichotomic type. They form a 

 network around the iiair, penetrate into it, and are sometimes so 

 abundant that they constitute a real packing to which the word 

 mycelium is more particularly applied. 



