114 CIRCULATION OF THE BLOOD. [BOOK I. 



37. Reader, the circulation of the blood is 

 carried on through all parts of the body, to which 

 it affords the means of life and health ; or, being 

 ill performed, is the fruitful source of lingering, 

 obstinate, and often incurable diseases, some whereof 

 almost baffle our skill and care ; and, while they 

 induce us to admit that the practice of veterinary 

 physic never will reach perfection, inspires the hope 

 that, by patient investigation, we may at least find 

 out the means of alleviating their evil tendency. 

 These considerations should excite particular at- 

 tention to the subject in hand, being that to which 

 all other functions are but subservient or conducive ; 

 respiration and digestion being more closely con- 

 nected with it than any other, and requiring a 

 corresponding degree of attention. The hearty 

 jointly with the lungs, occupies the cavity of the 

 chest, rather inclining towards the left side, against 

 which its point may be felt beating, whenever the 

 animal is agitated by exercise, or internally affected 

 by inflammatory complaints. Its figure is too well 

 known to render description necessary : in size it 

 approaches that of an ox, and, like it, is enclosed 

 in a membraneous sac, but very thin, not unlike a 

 tight purse. Another sac, called the heart-bag, 

 less tight, surrounds the former, but is never so 

 large, nor encumbered with fat like that of the 

 bullock. On opening this sac there issues forth a 

 fluid which turns to water, if it were not so already; 

 in the ox it is confessedly water, and rather more 

 in quantity than in the horse ; — the reason for 



