ON THE CONTAGION OF ITCH Oil MANGE. 447 
ing them, constitute one of the reasons for insisting so much 
on the frictions of the upper extremities. 
Here, then, are the facts which have led to an abridgment in 
the duration of the treatment, to the great advantage of the 
patient as well as of the administration. 
Let us say, once for all, that the patients set apart to deter- 
mine the effect of any medicament were submitted to the 
examination of the microscope before, during, and after treat- 
ment; that is to say, we have with great care established the 
facts: — ls£, that the patients harboured living acarus; 2 dly, 
at what precise moment the insects were struck with death ; 
3 dly, that no fresh hatching had taken place Let us add, also, 
that, on all occasions, those patients the most confirmedly itched 
were selected. 
In the first series of experiments, we have made trial, in 
their isolated state, of substances which, in combination with 
one another, possessed the property of curing the itch : for ex- 
ample, sulphur, fatty matter, and salt having potass for its base, 
mixed together in given proportions, possess a well known 
efficaciousness. But, is it to the sulphur alone, to the fatty 
matter alone, or to the salt alone, that the cure is to be ascribed ] 
Such was the problem put ; not hypothetically, for there were 
practitioners who contended that oil or friction killed the acarus 
by asphyxia. Sulphur mixed with oil proved no less effi- 
cacious; and the affinity of sulphur for the hydrogen of the 
fatty matter, by forming a fresh poisonous compound, yielded a 
ready explanation of the modus curandi. Moreover, this hy- 
pothesis failing, might not one come to the logical conclusion, 
that the sulphur broke up the grooves, and killed the acarus 
upon the spot] 
The task of reducing these opinions down to their proper value 
was not, therefore, without interest*. 
A. — Frictions with common Oil. — Two patients rubbed 
themselves with oil, twice a-day, for three days, according to 
directions given them. The acarus died, but the eggs but little 
disturbed in their development. 
B. — Frictions with powdered Sulphur and Oil, — 
two parts of the former to three of the latter : — Four patients, 
two at a time, were submitted to frictions with this mixture, 
morning and evening, from the day of their admission. One of 
them had acarus about the genitals. We found, twelve hours 
• The necessity for being clear and concise has obliged us, in the exposition 
of facts, to change the order we have followed in our experimentation, and some- 
times to confound under the same date the admission and discharge of patients 
submitted to a treatment occupying several days of interval. 
