ANATOMY AND PHYSIOLOGY. 



Ill 



akin which covers the body of a middle-sized 

 man. Through these pores, more than one-half 

 of what we eat and drink passes off by insensible 

 perspiration. During a night of seven hours 

 sleep, we perspire about forty ounces, or two 

 pounds and a half. At an average, we may es 

 timate the discharge from the surface of the 

 body, by sensible and insensible perspiration, at 

 from half an ounce to four ounces an hour. This 

 is a most wonderful part of the animal economy, 

 ar.d is absolutely necessary to our health, and 

 even to our very existence. When partially ob 

 structed, colds, rheumatisms, fevers, and other 

 inflammatory disorders, are produced ; and were 

 it completely obstructed, the vital functions 

 would be clogged and impeded in their move 

 ments, and death would inevitably ensue. 



Sensation. The nerves are generally consi 

 dered as the instruments of sensation. They 

 are soft white cords which proceed from the brain 

 and spinal marrow. They come forth originally 

 by pairs. Ten pair proceed from the medullary 

 substance of the brain, which are distributed to 

 all parts of the head and neck. Thirty pair pro 

 ceed from the spinal marrow, through the ver 

 tebra?, to all the other parts of the body ; being 

 forty in all. These nerves, the ramifications of 

 which are infinitely various and minute, are dis 

 tributed upon the heart, lungs, blood-vessels, 

 bowels, and muscles, till they terminate on the 

 skin or external covering of the body. Impres 

 sions of external objects are received by the 

 brain from the adjacent organs of sense, and the 

 brain exercises its commands over the muscles 

 and limbs by means of the nerves. 



Without prosecuting these imperfect descrip 

 tions farther, I shall conclude this very hasty 

 sketch with the following summary of the parts 

 of the body, in the words of Bonnet. &quot; The 

 bones, by their joints and solidity, form the foun 

 dation of this fine machine : the ligaments are 

 strings which unite the parts together: the 

 muscles are fleshy substances, which act as elas 

 tic springs to put them in motion: the nerves, 

 which are dispersed over the whole body, con 

 nect all the parts together : the arteries and veins, 

 like rivulets, convey life and health throughout : 

 the heart, placed in the centre, is the focus where 

 the blood collects, or the acting power by means 

 of which it circulates and is preserved: the 

 lungs, by means of another power, draw in the 

 external air, and expel hurtful vapours: the sto 

 mach and intestines are the magazines where 

 every thing that is required for the daily supply 

 is prepared: the brain, that seat of the soul, is 

 formed in a manner suitable to the dignity of its 

 inhabitant : the senses, which are the soul s mi 

 nisters, warn it of all that is necessary either for 

 its pleasure or use.* Adorable Creator! with 

 what wonderful art hast thou formed us ! 



Contemplation of Nature, vol. I. p. 64. 



Though the heavens did not exist to proclaim 

 thy glory; though there were no created being 

 on earth but myself, my own body might suffice 

 to convince me that thou art a God of unlimited 

 power and infinite goodness.&quot; 



This subject suggests a variety of moral and 

 religious reflections, but the limits to which I 

 am confined will permit me to state only the 

 following : 



1. The economy of the human frame, when 

 seriously contemplated, has a tendency to excite 

 admiration and astonishment, and to impress ut 

 with a sense of our continual dependence on a su- 

 perior power. What an immense multiplicity of 

 machinery must be in action to enable us to 

 breathe, to feel, and to walk ! Hundreds of 

 bones, of diversified forms, connected together by 

 various modes of articulation : hundreds of 

 muscles to produce motion, each of them acting 

 in at least ten different capacities, (see p. 40 5) 

 hundreds of tendons and ligaments to connect the 

 bones and muscles; hundreds of arteries to con 

 vey the blood to the remotest part of the system ; 

 hundreds of veins to bring it back to its reser 

 voir the heait ; thousands of glands secreting 

 humours of various kinds from the blood ; 

 thousands of lacteal and lymphatic tubes, ab 

 sorbing and conveying nutriment to the circulat 

 ing fluid ; millions of pores, through which the 

 perspiration is continually issuing ; an infinity 

 of ramifications of nerves, diffusing sensation 

 throughout all the parts of this exquisite ma 

 chine ; and the heart at every pulsation exerting 

 a force of a hundred thousand pounds, in order to 

 preserve all this complicated machinery in con 

 stant operation ! The whole of this vast system 

 of mechanism must be in action before we can 

 walk across our apartments ! We admire the 

 operation of a steam-engine, and the force it ex 

 erts. But, though it is constructed of the hardest 

 materials which the mines can supply, in a few 

 months some of its essential parts are worn and 

 deranged, even though its action should be fre 

 quently discontinued. But the animal machine, 

 though constructed, for the most part, of th 

 softest and most flabby substances, can go on 

 without intermission in all its diversified move 

 ments, by night and by day, for the space ol 

 eighty or a hundred years ; the heart giving 

 ninety-six thousand strokes every twenty-four 

 hours, and the whole mass of blood rushing 

 through a thousand pipes of all sizes every four 

 minutes! And is it man that governs these 

 nice and complicated movements ? Did he set 

 the heart in motion, or endue it with the muscu 

 lar force it exerts ? And when it has ceased to 

 beat, can he command it again to resume its 

 functions? Man knows neither the secret 

 springs of the machinery within him, nor the 

 half of the purposes for which they serve, or of 

 the movements they perform. Can any thing 

 more strikingly demonstrate our dependence 



