148 ANATOMY AND PHYSIOLOGY. 



of the circulation sometimes endeavored in imagination to trace the 

 effect which the stupendous fact at the knowledge of which he had 

 arrived would have on the progress of his favorite science ; and, it 

 may be, the hope and the expectation occasionally arose that the 

 inestimable benefit he was about to confer on his fellow men would 

 secure to him some portion of their esteem and confidence. What 

 must have been his disappointment when he found, after the publi- 

 cation of his tract, that the little practice he had had as a physician 

 by degrees fell off. He was too speculative, too theoretical* not 

 practical. Such was the view taken even by his friends. His 

 enemies saw in his tract nothing but indications of a presumptuous 

 mind that dared to call in question the revered authority of the 

 ancients ; and some of them saw, moreover, indications of a malig- 

 nant mind, that conceived and defended doctrines which, if not 

 checked, would undermine the very foundations of morality and 

 religion. When the evidence of the truth became irresistible, then 

 these persons suddenly turned round and said, that it was all known 

 before, and that the sole merit of this vaunted discoverer consisted 

 in having circulated the circulation. The pun was not fatal to the 

 future fame of this truly great man, nor even to the gradual though 

 slow return of the public confidence even during his own time ; for 

 he lived to attain the summit of reputation, and to see his great 

 discovery taught in all the medical colleges, as before stated. 



The parts of the circulating system most difficult to be understood, 

 are the valves of the heart and their action. Both these can be beau- 

 tifully shown in a cow's heart, the vessels of which have been cut 

 high up, and as little injured as possible. The hard suet being cleared 

 from the base of the heart, to show the bicuspid valve between the 

 left auricle and ventricle, pass the finger into the large opening of 

 the aorta (which is the vessel butchers often hang the heart by) 

 nearest the heart, when will be felt the semilunar valves at the 

 mouth of the left ventricle. These must be broken down by 

 cautiously introducing a scalpel, or penknife, and cutting and then 

 forcibly rupturing them with the finger. Having done this, close 

 all the openings on the side of the aorta, by tying them, or trans- 

 fixing them with a needle, and twisting thread round it, or putting 

 a small cork in the largest, fastening with needles, and twisting 

 thread round them, &c. Now pour water gently into the aorta, and 

 notice where it escapes. This will be by the left auricle, which is 

 to be cautiously removed (but not cut quite to its base), until the 

 valves are exposed. If water is now poured quickly into the aorta > 



