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MA£> I^Cfl—fctfZOOtflC MEfriftGITlS. 
presented isolated and faint traces of congestioned capillaries. 
Doubtless there were secondary lesions. There was no impac¬ 
tion, and no congestion nor inflammation besides that. This is 
worthy of notice, since the few whom I have found endeavoring 
to account for the disease, bring impaction and omastitis into 
play as causation. When these conditions are present in mad- 
itch, they must be simply co incidental, since this affection cer¬ 
tainly occurs without them. 
Etiology. 
In view of what is explained in the foregoing chapters, which, 
so far as I can find, reverses the generally accepted opinions about 
mad^-itch, I came to the conclusion that it is of a specific nature, 
due to a cause not yet identified positively, but which I suspect 
to be some virulent agent of the nature of ferments, some form 
of micro-organism generating a poison within the body, or outside 
of it in proper media and temperature for their growth and pro¬ 
liferation. This poison would act directly on the nervous sys¬ 
tem. The nature of the blood suggests that it is deeply altered, 
and that its organized elements have been attacked by some agent 
as effective as that which causes apparently similar changes in 
authrax. I took specimens to examine with the microscope, but 
they were putrid before I reached home. From some others got¬ 
ten lateral made cultures in various media—gelatinized beef 
broth, potatoe, etc., and raised crops of various microbes, but 
none of them I have as yet any reason to consider pathogenic. 
I tested all the feed—hay, corn, water of pond, during twelve 
days on some cattle bought for that purpose from a place where 
no disease had occurred, but failed to produce it. The water had 
again frozen before this occurred, however, and the field surface 
water, (in hoof prints), I had no opportunity to test. 
I took from one case a little serum from the arachnoid cavity,* 
the conjunctive tissue beneath rubbed surface, and a drop of blood 
in the heart, mixed the whole with a little tepid water, and inoc¬ 
ulated a one year old bull with this substance in the right ear and 
right side of neck. Ten days later the bull died with symptoms 
of mad-itch and presented its lesions at post-mortem examina¬ 
tion. Now this bull was purchased away from the pasture where 
