86 FIRST APPEARANCE OF THE HEART. 



Troy weight, at each contraction, and the whole quantity 

 of biood in the vessels to be thirty-three pounds, you will 

 have no difficulty in answering the question yourself. 



Emily. One hundred and fifty ounces, or twelve and 

 a half pounds, will be expelled from the heart each mi- 

 nute, consequently thirty-three pounds in two minutes 

 and thirty-six seconds, so that the whole mass of the 

 blood will go the round of the circulation twenty-three 

 times in an hour. What astonishing rapidity ! 



How wonderful that in so small a space of time, every 

 portion of blood sent out from the heart goes to the body, 

 thence to the lungs, and finally back to the heart again. 

 And with what astonishing force too the heart must act 

 to propel so large a mass ! 



Dr. B. This great power has always excited the at- 

 tention of physiologists, and at a time when mathematical 

 calculations were greatly in fashion in medical science, 

 many attempts were made to ascertain its exact quantity. 

 One philosopher performed a great many experiments, 

 and w^ent through many tedious calculations to ascertain 

 the power with which the heart expelled the blood, and 

 lo the result ! He found it equal to one hundred and 

 eighty thousand pounds ! Another, after going over a 

 field of investigation full as extensive, came to the con- 

 clusion, that it was five ounces and a half 1 Another 

 estimated it at fifty pounds, in which estimate he proba- 

 bly came nearer to the truth than either of the others. 



Being; the most essential of all the organs, the heart is 

 the first one formed in the organization of the higher ani- 

 mals. Jf the egg of a bird be examined in the first peri- 

 ods of incubation, the heart will be seen a hardly per- 

 ceptible speck, having already begun its motions, before 

 the rudiments of any other part can be observed. Many 

 of the other organs are sometimes found wanting, but 

 never the heart. Here it is, beating on untired from 

 the beginning; to the end of life. This finishes our ac- 

 count of the circulation through the heart. 



Emily. Now, I suppose we are to trace it in its pro- 



