ON MYoITIS. 
459 
ward appearance as a sure test of the seat of disease ; for though 
it is true that a part once injured is, cceteris paribus, more prone to 
take on morbific action than if it had not previously been affected, 
yet it does not follow that it may not escape, and some other part 
be diseased ; for it is not by any means an unfrequent occurrence, 
that two parts may be simultaneously injured : as, for example, a 
horse may cut or bruise his foot and spring the suspensory liga- 
ment at one and the same moment — two diseases entirely distinct 
from each other ; or he may spring the suspensory ligament and 
wrench the hock, so as to terminate in spavin ; indeed, the combina- 
tions of this kind are but too common. 
Again, we are too apt to consider every thickening of the back 
of the leg as an affection of the sineivs. Now every thickening 
of the back of the leg is not an affection of the tendons. Examine 
more closely into some of these cases, and you will find that the 
true tendons, the perforans and perforatus, are from knee to fetlock, 
when strained tight by the animal being made to stand on the leg 
under examination, clearly to be distinguished by the hand and 
fingers, beneath and through this existing thickening ; and if 
traced carefully, not a symptom of irregular surface or of abnormal 
density of fibre is to be detected ; while, on the other hand, in some 
cases the change of structure is clearly and only referrible to the 
tendons themselves. Now here are two distinct forms of disease : 
the first we endeavour to connect with our ideas of the affections 
of sinew by calling it a case of “ thickened sheath of the tendons 
while, in truth, it is not a disease of tendinous structure at all, but 
of cellular tissue, sometimes the result of an injury, or done by a 
single journey, but most generally the result of long-continued and 
repeated exertion when the parts are unfitted for it. Occasionally 
we hear of “ gummy legs,” and which, though any thing but a 
euphonious term, is rather expressive ; but I have never heard 
any interpretation of the term, but “ thickened sheath of the 
tendons.” Now I must confess that I have for many years looked 
upon this “ gummy leg ” as different from, and produced by causes 
rather dissimilar to, those of diseased tendons ; and, further, a state 
very often accompanying and secondary in importance to some 
other disease. 
Again, if we look at the ordinary relation of tendon to muscle, 
we shall find that the power of the one is equal to the endurance 
of the other ; but we sometimes find that the one is rather in 
excess over the other : this may arise from a natural defect, or be 
produced, in some measure, by the artificial state in which either 
the one or the other may be placed. 
The most general effect of derangement of function, or disease 
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