BIOLOGY AND HUMAN PROBLEMS 



ninety-nine parts of this knowledge have been obtained 

 during the past century, the full span of a single human 

 life. This fact makes the future seem quite rosy. 



In 1828 a new field was entered. Wohler made urea in his 

 laboratory. For the first time a product, until that day 

 known only as the waste of animal activity, was produced 

 by artifice. Henceforth all organic activity was inter- 

 pretable in the terms of chemistry. To-day the whole 

 sequence of chemical changes from the intake of raw food 

 to the resultant bone and muscle is pretty well mapped out. 

 The way in which the food breaks down during digestion, 

 the manner in which the blood acts as carrier of the re- 

 sultant constituents, and the method by which even the 

 synthesis of proteids occurs, can all be traced with a 

 considerable degree of accuracy. And from the knowledge 

 gained through studying normal metabolism, our bio- 

 chemists have learned much concerning the abnormal. 

 Medicine has profited. Pathologists already utilize chemical 

 tests to discover whether organs are functioning properly; 

 and the day is not far away when much organic deficiency — 

 whether hereditary or the result of disease — can be made 

 good by the compounds of the commercial chemist. 

 Insulin is the herald of these good tidings. 



In the third decade of the nineteenth century, biology 

 reached out again. Schleiden and Schwann demonstrated 

 that cells are the structural units of every organism, 

 whether animal or plant. This discovery, denounced in no 

 uncertain terms as an impossible theory for several years, 

 revised our whole concept of living things. It was, perhaps, 

 more important as a philosophical innovation than as the 

 opening investigation of the field of research now termed 

 cytology; nevertheless the study of the cell has yielded 

 concrete results of extraordinary value, considering the 

 limited period during which it has been carried on. Our 

 leading investigator in this department of knowledge, 



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