DEPILATING THRUSH. 



537 



2. Spores or conidia are small spherical or oblong cells, which 

 are réfringent, with a very distinct outline, the diameter of which 

 is nearly the same as that of the filaments at the expense of which 

 they are produced by segmentation ; they are often shaped like a 

 bead-roll, and exist in much larger number than the filaments, 

 rendering these latter almost imperceptible. As they are very 

 resistant to the various causes of destruction, they preserve their 

 vitality for more than one year (Siedamgrotzky). 



The trichophyton vegetates preferably in the packed bulbs and 

 in the hair itself ; at first it surrounds the lower parts of the former, 

 with its filaments forming an enveloping cloak or an aliform mem- 

 brane; later it penetrates into the sheath of the organ, becomes 

 implanted in its root, and produces an inflammation of the follicle, 

 which is soon followed by a loosening and falling out of the hair ; 

 lastly it invades even the substance of the latter, which becomes 

 slit, brittle, friable, and sometimes has its deep layers overrun with 

 conidia (spores) to such an extent as to leave no trace of the hair 

 structure. The fungi seem to thrive upon skins that are deeply 

 pigmented. 



The dimensions of spores and filaments vary according to the 

 animal species, and they may differ considerably when being ex- 

 amined comparatively with several animals of the same species. 

 Mégnin thought proper to admit two distinct parasitic species : 

 Trichophyton tonsurans in the horse and Trichophyton epilans in 

 the ox. But the dimensions of the parasite are of but secondary 

 importance, depending undoubtedly on more or less favorable con- 

 ditions of the soil. 



According to Grawitz, the fungi of depilating thrush softens 

 gelatin much more rapidly than that of favus. On agar, Tricho- 

 phyton is developed and produces a kind of grass, while Achorion 

 gives a star-shaped vegetation. 



Symptoms. Manifestations of depilating thrush vary accord- 

 ing to the animal species, race, localization of the dermatoraycosis, 

 its age, and alterations due to rubbings, bites, etc. The character- 

 istic symptom consists of round-shaped spots, mostly located on the 

 head, neck, and legs ; these spots are bare or covered with broken 

 hair ; at the outset their dimensions are nearly that of a lentil ; 

 later they become enlarged, till they reach the size of a silver dollar 

 or over. These spots remain sometimes disseminated, at other times 

 they become confluent and confounded in more or less extended 



