THE ITCH-MITE OF MAN. 55 
eggs 0.14mm). This species has been found upon man, ape, 
horse, sheep, lion, llama, ferret, and other animals. 
The itch-mite lives in self-made burrows just beneath the 
epidermis or scurf-skin. These burrows (fig. 29), called by 
physicians ‘‘acarian furrows,’’ extend through the deeper 
layers of the epidermis to and into the trueskin. During the 
existence of the mites in the burrows, which are similar to 
the underground tunnels made by a mole, the mite moults 
three times, without, however, greatly 
changing in general appearance ex- 
cept in size. The eggs, large in com- 
parison to the size of the mother, are 
elongate-oval, with a smooth skin. 
From 20 to 24 eggs are said to be de- 
posited at a time, and they hatch in 
4 or 7 days. Such eggs, if kept in 
moist surroundings, remain good from 
three to four weeks. The mites, if re- 
moved from the host, can also exist 
for a long time if kept moist, but 
die in four to six days in dry sur- 
roundings. The female mite, as she 
progresses in digging a burrow, lays 
the eggs behind her, and soon dies. 
These eggs can be seen in a regular 
row in the burrow (fig. 29). 

1a EO Bare se sui ar 
Stavchowing | aegmenta- We know the skin of the host is 
tion; cto d, eggs showing ° 
cabiyo; é. empty ess. constantly wearing off and as con- 
shells; the black spots are z 
excrement, Greatly en- stantly renewed by new growth from 
A eee any beneath. This being the case the eggs 
in the burrow will reach the surface just about in time to 
hatch and to permit the young animal to escape. These bur- 
rows are from one-twelfth to a quarter of an inch long and 
possess a serpentine form. They can be detected below the 
surface of the skin as a whitish dotted line, the dots corre- 
sponding to the eggs. Over the entrance made by the mite 
there is usually a little pimple on the skin containing a wa- 
tery fluid. When we try to obtain the mite by puncturing 
