PAPERS ON CHEMISTRY AND PHYSICS 161 



stereochemical structure of the molecule, and so one of 

 nature's most fundamental processes, that of digestion 

 and metabolism, may be quite as much chemical as bio- 

 logical. 



Other complex problems of biology can often be simpli- 

 fied by resolving them into their physical and chemical 

 components. Professor Lillie has shown that nerve cur- 

 rents, the biological basis of psychology, are essentially 

 electrical and chemical in nature. Also, Sir Wm. Bate- 

 son, an eminent authority on evolution, believes that all 

 its theories must be in accordance with facts of physics 

 and chemistry. It is from this point of view that muta- 

 tion, the act of differing from parent to offspring, has 

 been resolved into problems of these two departments. 

 Crystallization, diffusion, electric or magnetic lines of 

 force, and harmonic vibration are factors which make for 

 similarity between organisms from the same source; so 

 that to find conditions which would modify these factors 

 is to form a basis for the explanation of mutation. The 

 contribution of physics has been such conditions as tem- 

 perature and pressure, while the chemist has been study- 

 ing the effect of colloids on crystallization, all of which 

 show that mutation is not as obscure a process as it ap- 

 pears on the surface. 



The biological discovery of insulin as a cure for dia- 

 betes had little practical value until the chemist had 

 worked out a method of preparing it in quantity. The 

 biological method was to extract it from the pancreas 

 of a dog, by first destroying the pancreatic juices in order 

 that they would not digest the insulin. Since this proc- 

 ess required six months it was impractical, and the prob- 

 lem was turned over to chemists. After a year of re- 

 search they were able to prepare it from the sweetbreads 

 of cattle so that now the industry is able to supply the 

 18,000 people in the U. S. who take insulin daily. The 

 function of insulin is to destroy the excess sugar in the 

 blood, and the amount administered must be exactly in 

 proportion to this excess, for an overdose of insulin is 

 harmful to the patient. The difficulty is that in a given 

 dose the amount of pure insulin is not known, so that its 

 strength has to be determined by injecting it into a 



