APPARATUS FOR PHYSIOLOGICAL CHEMISTRY- 



BY DR. LAUDER BRUNTON, F.R.S. 



GENTLEMEN, you learnt from Dr. Burden Sanderson yester- 

 day the various modes of recording the movements of 

 the body and its parts. To-day we have to consider how 

 those motions are kept up. The old illustration that the 

 steam-engine resembles the human body has become so 

 hackneyed simply because it is so true, and because it 

 affords us the best means of illustrating the manner in 

 which the movements of the human body, or of any animal 

 organism, are kept up. In both the animal organism and 

 the steam-engine motion is kept up by the conversion of 

 chemical into mechanical energy in the process of combus- 

 tion. Now the products which are given off from the lungs 

 are the same as those given off from the funnel of a steam- 

 engine, viz., carbonic acid and water. You know that one 

 of the most ordinary methods of ascertaining whether a man 

 is dead or alive is to put a looking-glass before his mouth, 

 and notice whether it is dimmed or not. This simply means 

 that if the person is alive water is given off from the lungs, 

 and water being one of the products of combustion, its 

 condensation on the mirror affords a ready means of ascer- 

 taining that combustion is still going on in the body. 

 But, although the movements of the whole animal are kept 

 up by means of oxidation going on in the system, as you 

 see from the products of combustion being given off by the 

 lungs, yet Dr. Sanderson showed you yesterday that the 

 muscle of a frog would continue to contract after it had 

 been excised from the body. This proved to you that the 



