74 



ANIMAL CHEMISTRY. 



The child, indeed, will not grow, but neither 

 will it lose weight. 



II, in the adult man, the consumption of 

 force for mechanical purposes in 24 hours 

 be augmented beyond the amount restorable 

 in seven hours of sleep, then, if the equili- 

 brium is to be restored, less force, in the 

 same proportion, must be expended in me- 

 chanical effects in the next 24 hours. If 

 this be not done, the mass of the body de- 

 creases, and the state characteristic of old 

 age more or less decidedly supervenes. 



With every hour of sleep the sum of avail- 

 able force increases in the old man, or ap- 

 proaches the state of equilibrium between 

 waste and supply which exists in the adult. 



It is further evident, that if a part of the 

 forte which is available for mechanical 

 purposes, without disturbing the equilibrium, 

 should not be consumed in moving the 

 limbs, in raising weights, or in other labour, 

 it will be available for involuntary motions. 

 If the motion of the heart, of the fluids, and 

 of the intestines (the circulation of the blood 

 and digestion) are accelerated in proportion 

 to the amount of force not consumed in 

 voluntary motions, the weight of the body 

 will neither increase or diminish in 24 hours. 

 The body, therefore, can only increase in 

 mass, if the force accumulated during sleep, 

 and available for mechanical purposes, is 

 employed neither for voluntary nor for in- 

 roluntary motions. 



The numerical values above given for 

 the expenditure of force in the human body 

 refer, as has been expressly stated, only to a 

 given, uniform temperature. In a different 

 temperature, and with deficient nourishment, 

 all these proportions must be changed. 



If we surround a part of the body with ice 

 or snow, while other parts are left in the 

 natural state, there occurs, more or less 

 quickly, in consequence of the loss of 

 heat, an accelerated change of matter in 

 the cooled part. 



The resistance of the living tissues to the 

 action ,of oxygen is weaker at the cooled 

 part than in the other parts ; and this, in its 

 effects, is equivalent to an increase of re- 

 sistance in these other parts. 



The momentum of force of the vitality in 

 the parts which are not cooled is expended , 

 as before, in mechanical motion ; but the 

 whole action of the inspired oxygen is 

 exerted on the cooled part. 



If we imagine an iron cylinder, into 

 which we admit steam under a certain 

 pressure, then if the force with which the 

 particles of the iron cohere be equal to the 

 force which tends to separate them, an equi- 

 librium will result ; that is, the whole effect 

 of the steam will be neutralized by the re- 

 sistance. But if one of the sides of the 

 cylinder be moveable, a piston-rod, for ex- 

 ample, and offer to the pressure of the steam 

 a less resistance than other parts, the whole 

 force will be expended in moving this one 

 side that is, in raising the piston-rod. If 

 we do not introduce fresh steam (fresh force) 



an equilibrium will soon be established. The 

 piston-i od resists a certain force without 

 moving, but is raised by an increased pres- 

 sure. When this excess of force has been 

 consumed in motion, it cannot be raised 

 higher; but if new vapour be continually 

 admitted, the rod will continue to move. 



In the cooled part of the body, the living 

 tissues offer a less resistance to the chemical 

 action of the inspired oxygen ; the power 

 of the oxygen to unite with the elements of 

 the tissues is, at this part, exalted. When 

 the part has once lost its condition of life, 

 resistance entirely ceases; and in conse- 

 quence of the combination of the oxygen 

 with the elements of the metamorphosed 

 tissues, a greater amount of heat is liberated. 



Eor a given amount of oxygen, the heat 

 produced is, in all cases, exactly the same. 

 In the cooled part, the change of matter, 

 and with it the disengagement of heat, in- 

 creases ; while in the other parts the change 

 of matter and liberation of heat decrease. 

 But when the cooled part, by the union of 

 oxygea with the elements of the metamor- 

 phosed tissues, has recovered its original 

 temperature, the resistance of its living par- 

 ticles to the oxygen conveyed to them again 

 increases, and, as the resistance of other 

 parts is now diminished, a more rapid 

 change of matter now occurs in them, their 

 temperature rises, and along with this, if the 

 cause of the change of matter continues to 

 operate, a larger amount of vital force be- 

 comes available for mechanical purposes. 



Let us now suppose that heat is abstracted 

 from the whole surface of the body ; in this 

 case the whole action of the oxygen will be 

 directed to the skin, and in a short time the 

 change of matter must increase throughout 

 the body. Fat, and all such matters as are 

 capable of combining with the oxygen 

 which is brought to them in larger quantity 

 than usual, will be expelled from the body 

 in the form of oxidized compounds. 



III. THEORY OF DISEASE. Every sub- 

 stance or matter, every chemical or mecha- 

 nical agency, which changes or disturbs the 

 restoration of the equilibrium between the 

 manifestations of the causes of waste and 

 supply, in such a way as to add its action 

 to the causes of waste, is called a cause of 

 disease. Disease occurs when the sum of 

 vital force, which tends to neutralize all 

 causes of disturbance, (in other words, when 

 the resistance offered oy the vital force,) is 

 weaker than the acting cause of disturbance. 



Death is that condition in which all resist- 

 ance on the part of the vital force entirely 

 ceases. So long as this condition is not es- 

 tablished, the living tissues continue to offer 

 resistance. 



To the observer, the action of a cause of 

 disease exhibits itself in the disturbance of 

 the proportion between waste and supply 

 which is proper to each period of life. In 

 medicine, every abnorma condition of sup- 

 ply or of waste, in all pai ts or in a single 

 part of the body, is called disease. 



