oil INSKCT OF ITCH AND MANGE. 
377 
hairs, they are, however, scarcely halt' so long as those on the 
foot of the male insect, and the claw, as well as the sucker, 
is wanting. The inner hind feet {Jf) possess the rudiment 
of a claw, and under this a sucker like those on the fore feet, 
and near to it a fine hair almost as long as the foot itself. 
The difference of sex in the female insect is not easy to be distin¬ 
guished ; but the last described insect is the female; for when 
placed under a microscope eggs have very frequently been seen 
to proceed from her. If these are placed on the skin of a 
healthy horse, they change to young acari, and the animal be¬ 
comes itchy; while, from the first-described, or male insect, 
eggs have never been seen to proceed. 
The colour of the body of the male acari, when observed with 
the naked eye, is a glazed yellowish white, and that of the 
females a purer white, also glazed. The head and feet are in 
both sexes of a reddish rust colour, but the male insect is darker 
than the female. The body of the male, when placed under a 
miscroscope, appears of a dirty yellow, and that of the female 
under a bright light, of a blueish white colour. The suckers of 
both are white and transparent. 
The number of female insects appears to be much greater 
than that of the male, in the proportion of six or even ten 
to one. Many female acari are always found running freely 
about, while the males are seldom found alone but almost always 
coupled. 
The coupling seems rapidly to take place; for, when I have 
let several mites of both sexes run on a piece of paper, in the 
space of a very few minutes several pairs had united themselves 
together. How long they remained coupled is not known, but 
I have seen them in contact two, three, and even seven days. 
Neither is it cleaily ascertained at what age the young acari 
begin to couple ; it appears, however, to be very early, since 1 
have seen young mites that had not been more than one day out 
of the egg unite themselves with full-grown ones. 
After tile coupling the female becomes perce[)tibly rounder, 
and, in from three to five days, she voids an oblong 
white egg covered with a hard, glazed pellicle, and which is 
almost a third part of the size of the body of the mother. The 
egg is usually covered with a sticky moisture, by means of 
which it easily adheres to any thing with which it comes in con¬ 
tact. Sometimes the mite draws the egg with its hind feet to 
some particular s[)ot, but more fre(|uently she does not trouble 
herself about it. 
In the inside of the egg is found a substance like the white 
ol the hen’s egg, and which, even when j)laced untler a micro- 
