BIOLOGY IN HUMAN AFFAIRS 



lished as the second law of thermodynamics, and almost 

 equally serviceable." 



With this introduction, then, to what physiology is, 

 we may ask what are the present problems which occupy 

 its disciples, and what are its trends. Many problems are 

 old, as old as the science itself. Thus, in the field of the 

 circulation of the blood, many important problems which 

 are being actively attacked were already thoroughly 

 grasped and formulated by William Harvey, the father of 

 scientific physiology. What happens is that with each 

 generation of workers, with new methods and new angles 

 of attack devised, the old problems are reattacked and 

 pushed somewhat further towards a solution. Other ques- 

 tions appear quite new, but in many cases this is due to 

 the fact that it has only been with the marked advance of 

 the sciences, like physics and chemistry, that these prob- 

 lems could be properly formulated. The increasing im- 

 portance of biochemistry to the study of living processes 

 is quite obvious to anyone who has even superficially 

 scanned this field. Many problems connected with these 

 processes can be formulated, attacked, and solved only by 

 using the technique of chemistry. 



The marked advance of biochemistry as a method of 

 analyzing living processes may be granted as one of the 

 present trends of the physiology of to-day. The intimate 

 nature of muscular contraction is much better understood 

 as the result of chemical methods of investigation which 

 have involved a quantitative analysis of what happens to 

 the various compounds present in muscle during and after 

 contraction. The whole story of the regulation of the 

 acidity of the blood and the close relationship of blood and 

 breathing as carried out at the lungs, has depended almost 

 entirely upon biochemical technique for its present better 

 understanding. The study of the glands of internal secretion 

 and the hormones which they elaborate, has been one of 



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