352 ON THE CONTAGION OF ITCH OR MANGE. 
sensations such as a pin would cause, felt at irregular intervals, 
and on different parts of the body, continuing for forty-eight 
hours, and these were the only sensations felt by Francis. No 
eruption followed, to give us the idea that he had received any 
itch. Eight days afterwards, three fresh acarus were imprisoned 
upon his fore-arm ; and as he submitted to these experiments 
with fear and mistrust, I at the same time put three acarus upon 
my own left arm, and M. Piogey fixed a watch-glass over them. 
These six acarus, confined for eight days to the meagre diet of 
epidermic detritus, amid which they had been brought to us, 
became famished, empty and wrinkled, manifesting extraordinary 
activity. I soon felt under the watch-glass an itching, which 
increased to insufferable pricking. A pin slowly buried in the 
skin will convey a notion of the pain experienced. An hour 
afterwards, and for the remainder of the day, and at night, at ir- 
regular intervals, the same pricking sensations returned. When 
by chance the three acarus punctured the skin at the same time, 
the violence of the pain was such as instinctively to make me 
tap the watch-glass, with the view of shaking the skin, and in- 
terrupting the suction of the insects. Four-and-twenty hours 
afterwards the glasses were lifted. The acarus had tripled their 
volume. One of those placed upon Francis was dead ; and the 
five others could hardly move on account of their distention 
with lymph. The skin bore the marks of numerous prickings, 
such as are made by gnats ; and for some days was the seat of 
itchings, which lasted until the healing of the papulous eruption, 
which took place at every puncture. But this comprised all the 
mischief. Nothing further indicated that the insects had es- 
sayed to raise the epidermis, to make grooves in it. Francis 
remained in the hospital until the 10th July, without under- 
going any treatment, taking no bath, and yet experienced no 
eruption. 
These facts have led us to the conclusion, that the mange of 
horses is not communicable to men. 
Nor would it avail anything to urge, that the six imprisoned 
acarus were placed under exceptional conditions, and therefore 
could not produce contagion, while their presence for four-and- 
twenty hours under the watch-glass was intended to prove, that 
the acarus of the horse did not, like that of man, obey that 
pressing necessity of burying himself underneath the scarf-skin ; 
in a word, that it made no grooves. We must not forget, how- 
ever, that under the first experiment every liberty was given to 
the same three acarus which were afterwards confined under 
the glass without any production, through them, of mange : so 
that this first experiment, wherein no groove under the epidermis 
was made, capitally corroborates this second experiment, the 
