1 8 Veterinary Medicine. 



1838 (Lavergne, Carriere, Fehr), and 1852 (Bouley and Reynal). 

 The cryptogam was discovered by Gruby in 1842 in the ring- 

 worm of man, by Bazin in 1853 in that of the horse, by Gerlach 

 in that of the ox and dog in 1857-9, by Fenger in the cat in 1865, 

 by Perroncito in the sheep in 1872, and by Siedamgrotzky in the 

 pig in 1872. 



Essential Cause : Trichophyton Tonsurans. This cryp- 

 togam is found in the deeper layers of the scurfy concretion on 

 the affected part, in the hair follicles, bulbs and stems. It exists 

 in two forms — spores or conidia and mycelium or filaments. 



The spores are round or oval, 3/u. to 4/* (extremes 2ju, to 8/i.) in 

 diameter, with distinct outline and refrangent protoplasmic con- 

 tents. In man and ox they are larger than in horse or dog. 



The filaments are 4/x to 6/* thick (i/u, to 5/u. in dog), straight 

 or flexuous, and rarely branching. They may vary in size in one 

 host. 



The protoplasmic matter, inside the homogenous outer mem- 

 brane, may be continuous or broken up into segments, in certain 

 cases taking on the form of chains of spores. 



When invading the hair they extend longitudinally or trans- 

 versely, and destroy the cohesion of the hair cells, so that it tends 

 to break across, split up into smaller branching filaments, or to be 

 shed from the whole affected area. The resulting rounded bald 

 spots are very characteristic. Often the spores are so abundant 

 as to hide the presence of the mycelium, and in other cases the 

 filaments stand out prominently. 



Sabourand describes two forms : ( i ) T. Endothrix growing not 

 only on the skin but in the hair bulb and stem, which it renders 

 brittle, so that it cannot be removed from its follicle : hence its 

 inveteracy. This is not found on animals , but only on man and 

 especially on children. (2) T. Ectothrix grows only or mainly 

 outside the hair, though it may line its follicle and cover its stem. 

 The hair in this case retains its toughness and is not easily broken, 

 but is shed in one piece, and the way is left open for .successful 

 treatment. This is found on cat, dog, horse, calf, chicken, rat and 

 mouse, and may be transferred to man (adults mainly). On the 

 beard it produces patches in the form of a ring, with vesicles and 

 postules, and infiltration of the derma and hair bulb, surrounded 

 by pus. The spores of ectothrix are smaller and rounder than those 



