ON THE CONTAGION OF ITCH OR MANGE. 397 
On the 16th of May, the microscope could detect no trace of 
the insects. Ten others were laid upon the belly. 
30 th . — The epidermis was everywhere furrowed, the insects 
having commenced making grooves, though nothing resulted 
from them. The furrowing produced branny scales, a sort of 
slight pithyriasis. There is not the slightest eruption. The 
belly is shaved ; the skin appears white and smooth. Five 
fresh acarus are laid upon the part, and watched for half an 
hour. Two of them set to work immediately, digging into the 
epidermis, and concealed themselves underneath it. I sur- 
rounded the place they had taken possession of with a circle 
made by azotate of silver. The following morning I found them 
in the same place. The morning after they had deserted their 
first made cave, and had commenced another close to it. 
4 th June . — They have passed the boundaries of the circle ; 
the epidermis is lacerated ; the acarus are seen still alive under- 
neath its pellicles ; nowhere is to be detected any regular or de- 
terminate grooves. 
10 th . — Same observation. The belly is shaved, and ten 
more acarus put on. 
12 th . — The acarus living, commencing furrows, and after- 
wards abandoning them. 
2(M. — Same state. The acarus appear to have become dis- 
tributed over the body, for none are to be found, and the hair is 
growing again. 
The dog is kept in the hospital until the end of July, being 
all the while in perfect health. 
In fine, up to the 15th September, nothing had happened to 
excite any suspicion of the transmission of the disease. Thirty- 
five acarus had been placed, during May and June, upon the 
dog, without giving rise to any symptom of mange. 
Communication of Itch from Man to the Rabbit. 
Ylth May . — Eight human acarus were placed upon the back 
and belly of a rabbit. They disappeared in a furrow almost 
immediately. 
20 th . — No trace of the acarus to be found, nor did the animal 
shew any sign of mange. 
6th June . — Same observation. The belly was shaved, leav- 
ing exposed a fine rose-coloured soft skin, clothed by an epider- 
mis of extreme delicacy. Hardly were six acarus placed upon 
it than they attacked it and made their grooves, so that in 
twenty minutes four of them were completely covered, they 
being perfectly perceptible through the epidermic pellicle. 
8 fh . — The insects have remained concealed in a sort of groove, 
