THE KESPIBATOKY ORGANS. 261 



be a long time before lie would recover, and the circulation 

 and breathing be restored to their natural condition. We 

 will also suppose that he became thus distressed in going 

 half or three-quarters of a mile. We get rid of the super- 

 fluities, and drive him till he exhibits great fatigue, having 

 gone perhaps two or three miles. The respirations have 

 increased to two-thirds of the throbs of the heart. Still 

 the expirations and inspirations are nearly equal, and there 

 is very little if any sighing. He blows out freely and for- 

 cibly, recovering the natural breathing in much less time 

 than before. In the first case he would have been " dead 

 beat ; " in the second, by taking a pull, and easing him for 

 a short time, he would "come again," and make another 

 struggle. This would show that rapid respiration and 

 arterial action can be kept up if the organs are in a proper 

 state. The main muscle acting on the lungs, and assisting 

 in respiration, is the diaphragm. In forcible expiration 

 the abdominal muscles act with great power. It will be 

 useless to take much time to show that if an excessive de- 

 posit of fat exists, their aid will be much diminished. Fat 

 within the chest is laid in layers beneath the serous coat- 

 ing, and about the base of the heart. It materially affects 

 the breathing by encroaching on the pulmonary chamber, 

 and interfering with the expansion of the lungs, so that 

 the minute air cells cannot be filled to the extent of their 

 capacity as they can when freed from this obstruction. If 

 the heart is healthy, there is room within the pericardium 

 for all of its motions, contraction and expansion not being 

 greatly restricted by the outside coating of fat. But this 

 coating does effect the equalization, or rhythm of the puls- 

 ations, when the action is hurried, so it becomes necessary 

 to remove the obstruction here as elsewhere. 



The change in the blood, from the time it leaves the 

 heart by the arteries, till it is returned by the veins, after 

 having been aerated in the lungs, is a wonderful provision 



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