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W. L. WILLIAMS. 
clinical history and the pathology ; so much so, that with one 
quantity known, the other is promptly suspected or admitted. 
The co-habitation of tuberculous with healthy animals is fol¬ 
lowed by extension of the disease; its contagiousness is admit¬ 
ted, the existence of a specific virus assumed, and the micro¬ 
scope reveals tubercle bacilli. Again, a disease may be 
assumed to be contagious when some special form of bacillus 
is recognized as an essential factor in the disease, and experi¬ 
mental inoculation or extensive clinical observations support 
such a conclusion ; so a careful study of the preparatory and 
clinical history and symptoms of azoturia should suggest 
something as to its real pathology. 
The history of fit subjects for azoturia, their age, evident 
healthy, vigorous constitution, rich, healthful food and general 
management, all warrant us in assuming, as most writers 
claim, that the blood is the essential theater of the patho¬ 
logical changes ; and hence we may turn to a study of this 
tissue with strong hopes of learning the essential conditions 
in the production of the phenomena of this disease, and we 
are led to enquire, what changes are effected in the blood by 
that kind of feeding and management which leads to azoturia. 
First, it has been shown by Panum, Dennis and Pozziale, 
that the blood of animals at the age when horses are subject 
to azoturia, that is, in middle life, contains a markedly greater 
proportion of solids, especially of red corpuscles, and less 
water and salts, than animals either younger or older, except 
perhaps newly born animals. 
Andral and Tavanet have next shown that the strongest 
animals of a given species (and only these are subject to 
azoturia), show quite uniformly the largest proportion of red 
blood globules. 
In such animals it has been shown that by a change from 
hard labor with bad food, to lighter labor or rest, with dimin¬ 
ished respiration and richer albuminoid food, we produce a well 
marked further advance in the hyperalbuminotic condition, 
the blood, in such cases, attaining its maximum physiological 
amount of albumen and other solids, after a comparatively 
short period of rest, these constituents declining again with 
