MAN, THE ANIMAL 5 



limitations become evident as to what life can 

 and cannot do. 



Great importance is attached to a law govern- 

 ing natural phenomena and it is always given 

 first consideration in our thinking. Only a few 

 of Nature's laws have been revealed to man, — 

 more will be discovered with the progress of time. 

 It is, therefore, important that we appreciate how 

 these laws are discovered. First of all we must 

 emphasize that they are not something that man 

 has created or produced. They have always been 

 in existence so far as we can determine, i.e., the 

 laws of life have been true ever since life began; 

 secondly, that their final formulation is the result 

 of many different minds studying the problem. 

 Often the statement of these laws has some man's 

 name connected with It because he had the kind of 

 insight which enabled him to phrase correctly the 

 relations of facts already known. In biology we 

 have the Cell theory of Schlelden and Schwann or 

 VIrchow's formula "omnis cellula e cellula," both 

 of which are now regarded as biological laws. 

 These and similar phrasing of the conditions in 

 living protoplasm were not regarded as laws of 

 life until long after their first publication. Many 

 Independent observers studying the phenomena of 

 life had to verify all such statements until a large 

 mass of data was accumulated, all of which veri- 

 fied the preliminary hypothesis. If no exceptions 



