268 PHYSIOLOGY. 



Now as two ounces of blood are thrown out of the heart at 

 each beat, thirty-five pounds on an average, must pass through 

 the heart every three minutes ; seven hundred pounds every 

 hour; and sixteen thousand pounds, or eight tons, every 

 twenty-four hours. 



29. Dr. Barry states, that the quicker the blood circu- 

 lates the sooner will ther machine wear out. Now, suppose 

 that the pulse of a temperate man be seventy in a minute, 

 and by the use of ardent spirits he forces it up to eighty- 

 five, then instead of living seventy years, his number of pul- 

 sations will be finished at the age of fifty-six ; thus cutting 

 short his life fourteen years. 



30. The heart beats more than one hundred thousand 

 times in twenty-four hours, and sometimes continues to beat 

 thus for one hundred years. What other machine so com- 

 plicated, could last as long ? And still it is made of nothing 

 but flesh. How strange that it should act so long, without 

 growing weary ! Truly is it said, that " man is fearfully and 

 wonderfully made !" 



31. Some physiologists consider the heart the only mo- 

 ving power of the circulation : Others think that the arte- 

 ries aid by their contractile power. Others still believe that 

 the capillary vessels have a kind of absorbing and propelling 

 force, independent of the heart and arteries, while a last 

 class ascribe the circulation to a self-moving power in the 

 blood itself. All these theories may have some truth in them, 

 but they err in being too exclusive. 



32. That the heart is the chief moving power of the 

 blood is generally admitted. If the heart of a frog be ta- 

 ken from the body and placed in warm water, it will con- 

 continue to contract and dilate with great force for a con- 

 siderable time. This would seem to prove that its action 

 does not depend on the contact of air and blood. In ser- 

 pents the heart retains this power a long time after death; 

 and it has been known to contract at least four days after 

 life appeared extinct. The heart of a sturgeon was cut out 



