442 
MR. VINES IN REPLY 
that, by placing the itch acari on the human being, the h^rse 
acari on a healthy horse, and sheep acari on a healthy sheep, the 
itch, and mange, and scab, will after a certain time be produced; 
and that these diseases will increase or diminish in proportion 
as the insects are suffered to multiply or are destroyed. I will 
here cite an experiment first made by Walz, which I have 
frequently repeated, and which I consider as a very satisfactory 
proof of the insect theory. From the first appearance of mange 
on any particular sheep or horse, the animal was every day 
carefully examined, and every insect that was seen was picked 
out and destroyed : after this had been continued for some 
days, the disease healed of itself, while in other animals, attacked 
about the same time, and on whom this treatment was not pur¬ 
sued, it daily increased. 
6. It is exceedingly probable from this, that the acari are the 
sole cause of true itch and mange, at least if these diseases 
arise from infection. The results of all the experiments hitherto 
made by inoculating sound animals with the matter taken from 
itch or mange sores shews it to be most probable that no other 
mode of infection or contagion exists. 
7. Should any one, however, still believe that the disease is 
not produced by the acari, but by some matter which they 
carry away with them from the diseased animal on which they 
previously had existed, let him recollect this well-established 
fact, that, when fruitful female acari are placed on a healthy 
animal, a disease is produced which is not easy to be got rid of; 
but when male acari alone are placed on the animal, they pro¬ 
duce only very slight traces of the disease, and which vanish of 
themselves with the termination of the life of the insect. Now 
were the acari only bearers of the matter of contagion, and not 
themselves the cause of it, would not the male insect be as 
efficient as the female? 
8. Hence arises the following reply to the foregoing question :— 
That the acari are only a product of the itch and mange, as 
descending from other acari; and that, in consequence of their 
power of producing these diseases, they must be considered as the 
real cause thereof. 
MR. VINES IN REPLY TO SOME REMARKS OF THE 
EDITOR. 
Sir,—I CORDIALLY join you in hailing with delight” the 
formation of ‘‘The English Agricultural Society;” and it was 
chiefly for the public pledge, “ to take measures for improving 
