304 
ACARUS SCABIEI. 
two days; so did a labourer, who had used the brute in some field 
work during a few hours : and this went on till more than thirty 
persons, and several other horses attached to the farm, were in- 
fected with itch. The mangy animal was therefore got rid of, and 
being sold to a miller, he and his men were forthwith attacked with 
itch, merely from having put their hands on the back of the pur- 
chase. A cow also, which had rubbed her neck against the man- 
ger of the horse, contracted itch like the rest.” Hertwig*, of 
Berlin, relates that he once saw the disease communicated to a 
horse by a cat which had lain on his back while he stood in the 
stall. The same authority declares that he himself has had per- 
sonal experience of the infectiousness of this disease, and relates 
the following experiment which was made by Herr Schade, a ve- 
terinary student of Berlin. Eight horse acari, of both sexes, were 
placed on the skin of the arm, and confined there by a piece of fine 
paper fastened on by means of adhesive plaster : “ Five minutes 
after, a terrible itching arose, which continued, with periodical in- 
crease and decrease, for five days. After the lapse of thirty-two 
hours, only four of the acari were to be found on the skin. Se- 
veral 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 neigh- 
bourhood of these spots, were to be seen small hair-like passages. 
On the fifth day these passages were more perfectly formed, and 
were easily perceptible with the naked eye. One of them was 
nearly three-fourths of an inch long, and divided at the end like a 
fork; they all looked like smooth, red, slightly elevated lines, 
passing in different directions. When cut through with a lancet, 
they were. found to be hollow, and sometimes in and sometimes 
immediately under the outer skin. On these passages, or rather 
near to them, -were small bladders, which contained a clear fluid. 
The acari were neither to be found on the skin nor in the passages 
or bladders. From the fifth until the twelfth day the irritation gra- 
dually diminished, and at length entirely ceased. The bladders 
gradually dried up; the passages became less visible; and on the 
twelfth day the upper skin appeared covered with little dry scabs, 
which easily loosened themselves, and left behind a healthy skin.” 
Professor Hertwig remarks on this experiment, that it proves 
that horse acari wull pass on to the human being, and thereby cause 
an itchy eruption on the skin ; and, also, that in many cases the 
disease is not of long duration, and will get well of its own accord. 
But, in opposition to this last inference, Greve states that in many 
cases the disease produced in the human subject by horse acari 
will last from three to eight weeks. 
* Veterinarian, vol. xi. (vol. vi, New Series.) 
