INFLAMMATION.] 



THE HORSE, AND 



[iNFLAMMATIOlT. 



proportion. This is, therefore, something more 

 than simply a common relaxation. The whole 

 may be considered as a necessary operation of 

 nature. Owing to this dilatation, there is a 

 greater quantity of blood circulating in the 

 part, wLich is in accordance with the common 

 rules of the animal economy ; for whenever a 

 part has more to do than simply to support 

 itself, the blood is there collected in a larger 

 quantity ; and nature never errs. The swelling 

 is produced by an extravasation of coagulable 

 lymph, with some serum; but the lymph 

 differs from the common lymph, in conse- 

 quence of passing through the inflamed vessels. 

 It is this lymph which becomes the uniting 

 medium of inflamed parts. Vessels shoot into 

 it, and it has even the power of becoming 

 vascular itself. The pain proceeds from spasm. 

 When a part cannot be restored to health, 

 after injury by inflammation alone, or by 

 adhesion, then suppuration, as a preparatory 

 step to the formation of granulations, and the 

 restoration of the part, takes place. 



An increased action of the vessels is now 

 universally regarded as the proximate cause of 

 inflammation. This opinion is greatly sup- 

 ported from a review of the several existing 

 causes of the affection, which, being in general 

 of an irritating nature, must, when applied to 

 any living or sensitive parts, occasion a preter- 

 natural exertion of the vessels. The method 

 of cure, as we shall presently show, tends also 

 to coiifirm this doctrine with respect to the 

 cause of inflammation. 



SYMPTOMS OF INFLAMMATION FURTHER 

 CONSIDERED. 



The essential symptoms are swelling, heat, 

 and pain. — Swelling.— Thh effect arises from 

 several causes. Eirst, from the increased quan- 

 tity of blood in the vessels. Second, from the 

 effusion of coagulating lymph and the deposi- 

 tion of a new matter. Third, from the inter- 

 ruption of the absorbents, or their incapacity 

 to perform their office or functions. 



Heat. — It was formerly imagined that heat 

 was produced by the attraction of the red glo- 

 bules, of which blood is composed, against the 

 »ide3 of the vessels. Modern philosophy, how- 

 ever, teaches us, that a fluid may flow with the 

 utmost velocity through a pipe, for a thousand 

 years, without producing a single particle of 

 256 



heat. The most commonly received opinion 

 now is, that the production ot animal heat de- 

 pends on the different degrees of power which 

 arterial and venous blood have to combine with 

 caloric ; whilst in the minute arteries, the blood 

 is combined with certain substances. In con- 

 sequence of this, its capacity is diminished, and 

 heat is given out. When the venous blood, 

 however, has been freed from such substances 

 in the lungs, its capacity is increased, and 

 the heat which is given out by the decom- 

 position of the air which we inhale, is ab- 

 sorbed. These facts show that the augmented 

 heat of inflammation arises from the increased 

 velocity of the circulation in the part affected. 

 More blood is transmitted into the minute ar- 

 teries ; the capacity of a greater quantity of 

 this fluid for heat is of course necessarily in- 

 creased, and more caloric extracted. 



Faiti. — This is observed to be the greatest 

 during the diastole of the arteries. The affec- 

 tion is probably owing to the unnatural state 

 of the nerv^es, and not to mere distension, as 

 many have asserted. Were the latter cause a 

 real one, the nain would be proportioned to it, 



THE BLOOD IN INFLAMMATION. 



Blood, when taken out of the living vessels, 

 spontaneously separates into two distinct parts; 

 the serum, and the crassamentum. The latter is 

 a compound substance, consisting chiefly of co- 

 agulating lymph and red globules, which are 

 the heaviest ingredients in blood. Blood taken 

 away from an animal affected with inflam- 

 mation, is longer in coagulating, and coagu- 

 lates more firmly than under any other cir- 

 cumstances, lieiice, the red globules not 

 being so soon commingled with the lymph, 

 descend by their gravity ; and being moro or 

 less divested of the red colouring matter, they 

 are, from their appearance, termed the buffy 

 coat, or inflammatory crust. The firmer and 

 more compact coagulation of the lymph presses 

 out an unusual quantity of serum from it, and 

 the surface of the sizy blood is often formed into 

 a hollow, the edges being drawn inward. These 

 changes are, in some cases, a more infallible sign 

 of the existence of inflammation, than the state 

 of the pulse itself. At the same time, they are 

 probably only a criterion of some unusual ope- 

 ration going on in the system. In peritoneal 

 inflammation, the horse, sometimes, seems to 



