EXPERIMENTS MADE ON SHEEP WITH THE INSECT, &C. 635 
formed, which sticks fast upon the skin. The skin itself in the 
neighbourhood of the scurf is hard and of a yellowish-blue colour, 
and by rubbing seems very irritable. At different points eight 
little insects can be counted, which are seen only on the skin, 
and not amongst the wool. — 16th to 18th days : The scurf both in 
extent, and thickness increases, and has a dark yellow surface. 
The change in the skin observed yesterday spreads itself more 
and more; the insects increase in size, but their number lessens: 
the sheep seems to wish to rub the infected part with its lips. — 
From the 19th to the 31st day : The scurf spreads itself, as well 
as the change of skin, wider and wider, so that the disease is now 
five inches in circumference. The insects are very much in- 
creased, and now there can be no doubt of the real existence of the 
scab : on this account the experiment was put an end to. The 
sheep on the 14th and 23d of November was washed with Walz’s 
wash, and the scab was perfectly cured. 
Experiment No. 4. 
Experiment with the Moist Discharge from under the Scab . — 
(Sheep No. 6.) — I endeavoured, on the 7th of October, to com- 
municate the disease to the sheep marked No. 6, in the following 
manner : — I raised from one of the most diseased sheep a scab 
from the skin with great care, so as not to produce any bleeding. 
I then procured some of the matter which was underneath the .scab 
by means of the end of a knife, and then rubbed it upon two spots 
on the back of the healthy sheep, at a distance from each other, 
and from which a small quantity of wool had been previously 
clean removed, but so carefully as not to injure the skin : the wool 
around was then pressed together over the spot, and the sheep 
was put back into his former stall, and kept perfectly separated 
from all others. 2d day, 8th of October : The skin appears in 
some degree red and warmer than natural ; on the spots and to- 
wards the evening their surfaces were more moist than before. — • 
3d day, 9th of October: About noon, the skin on the part appeared 
of a pearly colour, with soft, thin, and loose scabs, of a yellowish 
colour : there was not the least trace of insects to be seen, and the 
degree of the irritation not to be altered. — 4th to the 10th day, 
from the 10th to the 16th of October : The condition of the spots 
continues the same, and the surrounding parts are perfectly sound. 
- — 11th day, 17th of October : The scurf is now somewhat harder, 
and more brown, and firmer fixed to the skin. When the spots 
are rubbed, the animal shews no pleasure. There is not the 
slightest trace of insects. — 12th to 14th day, from 18th to 20th of 
