76 
GEORGE MULLER. 
12.—Herpes tonsurans. 
Trichophyton tonsurans grows frequently upon the skin of 
cattle and dogs, more rarely upon that of horses, goats and cats, 
and least commonly upon that of sheep and pigs. It causes a 
malady that is variously known as herpes tonsurans, tinea decal- 
vans, tinea tonsurans, porrigo decalvans, ring-worm, borkenflechte, 
glatzflechte, teigmaul, teiggrind, etc. It is transmissible from 
animal to animal, and from animal to man. On rabbits it grows 
only after direct inoculation. 
The fungus consists of filaments which branch but sparingly, 
and of conidise possessed of great powers of resistence, and usually 
arranged in chains. Its favorite location is between the hair and 
the root sheath; but it soon penetrates into the epidermic cells 
and inside the hair itself, so that the central canal often shows 
large collections of spores. 
The mycelium and conidise may vary considerably in size; so 
much so that Megnin has described two species, a Trichophyton 
tonsurans of the horse, cat and dog; and a Trichophyton epilans 
of cattle. He differentiates these not only by the different sizes 
of the spores, but also by the fact that trichophyton epilans is 
much more difficult to transplant to horses’ skins and is much 
more intractable than is the other variety. 
Ziirn describes the appearance of herpes tonsurans as follows : 
“ The eruption shows itself as small, round, lentil to dollar- 
sized, partially or completely bald, sharply limited spots, often 
placed side by side at regular intervals or, more rarely, confluent. 
Confluent spots are seen most frequently in cattle, less often in 
the dog and the horse. The affected spots themselves are cov¬ 
ered by greyish-white, asbestos-like scales; older cases showing 
doughy, yellowish-grejr or brown, or even brownish-red, leathery 
scales. These form thick crusts, which are often 2-8 mm. in 
thickness, in which the hairs, loosened from their follicles, are 
found entangled.” When these crusts fall off, or are artificially 
removed, there appears a suppurating surface, which heals spon¬ 
taneously. Marked itching is always present. The eruption 
usually appears first on the head and neck in cattle, and on the 
middle of the back in horses, and it spreads thence further over 
the body. 
