348 ON THE CONTAGION OF ITCH OR MANGE. 
from caressing a mangy dog, narrated by Biett ; and the pre- 
tended cases of contagion reported by Viborg* and Mouronval t. 
We dispute the existence of mange in the fox, the monkey, 
the ox, the rabbit, the mouse, the pig, the ass, and the lion ; 
notwithstanding Walz, Gervais, Derfeuille, sen., Gohier, Koch, 
Hering, Bateman, Greve, and Alibert, assert, some of them, 
that they have actually seen insects upon such animals when 
they were mangy ; others, that the disease has spread from the 
animal to man; though not one of these authors has given the 
characters denotive of the sarcoptes they pretend to have found. 
The only fact, however, we shall make a reservation of, is, that 
declaring that the disease in such animals has caused cutaneous 
affections in man. 
The second category includes such facts as have relation to 
animals affected with mange, upon which acarus appears really 
to have been found ; as, for example, the horse, the camel, the 
goat, the sheep, the cat, and the kangaroo, have all presented 
disease of skin caused by the presence of particular insects 
which have been observed by the microscope, and of which de- 
scriptions, more or less perfect, have been given. Not that they 
have described the characters peculiar to each of these varieties of 
acarus ; for if, by way of example, we wished to distinguish be- 
tween the sarcopte of a sheep and that of a cat, according to 
Hering’s descriptions of them, the thing would turn out very 
difficult. A few hairs, more or less, the volume of the insect, the 
length of its feet, such are the distinctive marks by which authors 
pretend to recognise the various acarus. We feel no hesitation 
in asserting, notwithstanding the labours of Gervais, Hering, 
Dujardin, &c., that the entomology of acarus is yet to come. 
Vague descriptions are unsatisfactory when our business is with 
insects requiring an attentive observation under the microscope, 
in order that no confusion may be made among them. Be this, 
however, as it may, the acarus of the horse has been described 
or represented by Loutreig, Saint Didier, Bose, Raspail, Hert- 
wig, Gervais, Dujardin, and M. D. Got, whose inaugural 
thesis is an excellent monograph on mange in animals in general. 
Mange among horses is so common, and its sarcopte so nume- 
rous, that the slightest attention is sufficient to discover it amid 
the epidermic detritus occasioned by the disease. The acarus 
of the camel has been superficially described by Gervais ; that 
of the goat by Hering; that of the sheep by Walz, Linneus, 
Morgagni, Hering, and Hertwig ; that of the cat by Gohier, 
Boze, Hering, and M. Rayer, who has given drawings of it more 
complete than that published at the present day. The existence 
* Veterinar sels kapdeel, vol. ii, p. 194. 
f Mouronval — Recherches et Observations sur la gale; 8vo, Paris, 1822, p. 10. 
