CHEMICAL PHYSIOLOGY. 27 



THE PKESENT POSITION OF CHEMICAL PHYSIOLOGY.* 



By Professor W. D. HALLIBURTON, M.D., F.R.S. 



KING'S COLLEGE, LONDON. 



AN engineer who desires to thoroughly understand how a machine 

 works must necessarily know its construction. If the machine 

 becomes erratic in its action, and he wishes to put it into proper 

 working order, a preliminary acquaintance with its normal structure 

 and function is an obvious necessity. 



If we apply this to the more delicate machinery of the animal body 

 we at once see how a knowledge of function (physiology and pathology) 

 is impossible without a preliminary acquaintance with structure or 

 anatomy. 



It is therefore not surprising, it is indeed in the nature of things, 

 that physiology originated with the great anatomists of the past. It 

 was not until Vesalius and Harvey by tedious dissections laid bare the 

 broad facts of structure that any theorizing concerning the uses of the 

 constituent organs of the body had any firm foundation. 



Important and essential as the knowledge is that can be revealed by 

 the scalpel, the introduction and use of the microscope furnished 

 physiologists with a still more valuable instrument. By it much that 

 was before unseen came into view, and microscopic anatomy and phys- 

 iology grew in stature and knowledge simultaneously. 



The weapons in the armory of the modern physiologist are multi- 

 tudinous in number and complex in construction, and enable him in 

 the experimental investigation of his subject to accurately measure and 

 record the workings of the different parts of the machinery he has 

 to study. But preeminent among these instruments stands the test- 

 tube and the chemical operations typified by that simple piece of glass. 



Herein one sees at once a striking distinction between the mechanism 

 of a living animal and that of a machine like a steam engine or a 

 watch. It is quite possible to be an excellent watchmaker or to drive a 

 steam engine intelligently without any chemical knowledge of the 

 various metals that enter into its composition. In order to set the 

 mechanism right if it goes wrong all the preliminary knowledge which 

 is necessary is of an anatomical nature. The parts of which an engine 

 is composed are stable; the oil that lubricates it and the fuel that feeds 



* Presidential address to the Physiological Section at the Belfast Meeting 

 of the British Association for the Advancement of Science. 



