542 



DISEASES OF THE SKIN. 



generally by eating mice which are affected by it. Gerlach has not 

 succeeded in communicating it from the chicken to the horse, ox^ 

 and dog. In experiments undertaken by Schutz, the inoculation 

 of cultures of favus from the chicken has only given positive 

 results upon poultry ; it has remained unsuccessful upon rats, 

 guinea-pigs, pigeons, and mice. The fine and tender skin of young 

 animals is very favorable for the development of Aehorion. 



Morphological considerations upon the Achorion of 

 ScHŒNLEiN. This parasite produces, upon the surface of the skin, 

 more or less thick crusts, depressed in the centre, and cup-shaped — 

 favi or scutula small shields which are formed exclusively of 

 fungi, and represent, so to speak, a pure culture of the achorion. 

 Microscopic examination demonstrates their packed texture and 

 permits us to recognize filaments in it (mycelium, sporophorio 

 tubes) and spores (conidia). Morphologically these elements re- 

 semble those of the trichophyton. The filaments, the diameter of 

 which varies from 2 to 5 are at times elongated, very fine, not 

 encysted, sometimes shorter and thicker, ramified, articulated, in- 

 flated like a club and with granulous contents ; they are separated 

 by spherical or ovoid spores ; they are quite rare at the beginning 

 of the disease, but they exist in considerable numbers at a more 

 advanced stage ; their diameter differs little from that of sporophoric 

 tubes, by which they are generated through segmentation. The 

 achorion penetrates into the pilous follicles ; later, it invades the 

 hair itself or the quill of the feather, which becomes atrophied at 

 the root and falls out. Its filaments abound also between the epi- 

 dermic layers. 



Quite recently Schutz has cultivated the achorion of the chicken 

 upon peptonized gelatin at a normal temperature. The inoculation 

 of these cultures upon the chicken has given successful results. 



According to Quincke,^ favous thrush may be produced by three 

 different fungi. 



Symptoms. 1. Favus op mammals. The disease is charac- 

 terized by dry scabs in our animals ; they are brownish or yellowish 

 gray or silver white upon their surface, and white or sulphur yellow 

 in their deep layer. . These scabs have a circular form, their diam- 

 eter does not exceed that of a ten-cent piece, their thickness some- 

 times reaches one-half of a centimetre. They occasion atrophy of 

 the hair and a slight depression of the integument. They are 



1 Quincke: Archiv fiir experiment. Pathol, u. Pharmakol., 1887. 



