162 ILLINOIS STATE ACADEMY OF SCIENCE 



rabbit and measuring the amount of sugar destroyed. 

 The present problem of the chemist is to prepare a com- 

 pound of such purity that its strength will be known 

 directly, thus eliminating the trial and error method. 



We have thus shown how each science is dependent 

 upon the others. It may have become evident that when- 

 ever one science has contributed to another, the contribu- 

 tion comes back much more useful to its original depart- 

 ment. The chemist borrowed the electron theory from 

 the physicist, developed it as an explanation of oxidation, 

 then returned it to the physicist much more valuable be- 

 cause now he could use it in explaining the Voltaic cell 

 and the storage battery. In the same way the spectrum 

 came back to the physicist in the form of the spectro- 

 scope which he could use in explaining the dark line spec- 

 trum of the sun and in determining the composition of 

 other stars. The biologist's knowledge of enzymes was 

 greatly increased by loaning them out to the chemist for 

 use in stereochemistry. Biological methods could never 

 have found that the ferment's choice of foods depends 

 upon so insignificant a thing as the interchange of a few 

 hydrogen and hydroxyl groups. 



It is such illustrations as these which show that if the 

 inter-relation of the sciences is put to practical use, as is 

 being done in the border-line sciences, it will lead to a 

 greater exhaustiveness and accuracy in scientific re- 

 search. 



