437 
OR INSKCT OF ITCH AND MANGE. 
they had to look after and attend on mangy horses ; and I have 
had personal experience of the infectiousness of this disease. 
Fioni this last-mentioned fact I know for a certainty that the 
horse acari will pass on to the human being, and spread over 
his whole body—pierce through the skin, and speedily reduce it 
to a diseased state, very much resembling mange, and thereby 
cause, especially during the night, a dreadful itching*. 
In order to ascertain with certainty the consequence of the 
attack of these insects, Herr Schade, a very attentive student at 
the veterinary school in this town, resolved to place some acari 
taken from a horse on his own body. For this purpose he took 
five female and several male insects, and, placing them on the 
naked skin of his left arm, covered them with a watch glass, and 
fixed this on by means of a pitch plaister. The experiment could 
not, however, be continued long in this manner, for the w'atch- 
glass was pressed so close to the skin that its edges caused deep 
furrows and very great pain; it was therefore removed on the 
second day : but Herr Schade renewed the experiment by placing 
eight acari of both sexes on the skin under his arm, which he 
covered with a piece of fine paper, about four inches in circum¬ 
ference, and fastened this on by a strip of adhesive plaister. 
The following were the consequences : — 
In five minutes after the acari were placed on the skin a terri¬ 
ble itching arose, which continued with periodical increase and 
decrease for five days. 
After the lapse of thirty-two hours, only four of the acari were 
to be found on the skin. Several elevated red spots, of the size 
of a pin's head, were, however, visible on it, and on one of these, 
the head of which was slightly tinged with yellow, were two 
minute eggs; while in the neighbourhood of these spots were to 
be seen small hair-like passages. These appearances continued 
unchanged on the following day. 
On the fifth day these passages were more perfectly formed, and 
were easily perceptible with the naked eye. One of them was 
nearly three-quarters of a inch long, and divided at the end like a 
fork ; they all looked like smooth, red, slightly elevated lines pass¬ 
ing in different directions. When cut through with a lancet, they 
were found to be hollow, and sometimes in, and sometimes imme- 
* The difference between this quadruped itch and the real itch in the 
human bein^ is, so far as I can see, this, that the vesicles arc yellower, and 
generally larger in the former than the latter, and have also more redness of 
the skin around them. The most important difference, however, between 
these two disorders of the skin is, that that derived from the animal spreads 
over the face and head, which parts are, as is well known, never attacked by 
the real itch of the human being. Even on the head the itching caused by 
the animal itch it incessant, and very great. 
voi.. XI. 3 m 
