HISTORICAL DEVELOPMENT OF ZOOLOGY 451 



the witch doctor with his charms to conquer the evil spirits. 

 Swampy regions where the "bad air" caused yellow fever 

 and malaria in the days of our grandfathers have become 

 healthful dwelling places since man through science has 

 learned that mosquitoes, not the air, are responsible for the 

 malaria and yellow fever. The United States succeeded in 

 building the Panama Canal after other nations had been 

 forced to admit defeat in the attempt, not so much because 

 of superior engineering skill but as a result of knowledge 

 of the manner in which certain diseases are spread. The 

 diseases which killed off the workmen in the earlier attempts 

 were controlled by the American engineers through a scien- 

 tific knowledge of their causes which was not available 

 before. 



Through the information which the sciences have fur- 

 nished us we now look upon the entire universe as gov- 

 erned by definite laws. Ignorance and superstition fall 

 before the attack of knowledge. In the advance of our 

 learning and of science each generation witnesses the dis- 

 covery of new laws and principles governing nature. Many 

 of these new laws and principles have application for living 

 things as well as for lifeless material. Through these dis- 

 coveries man has learned how to make the forces of nature 

 serve him. In this discussion it is not worth while to go into 

 the details of how man discovered that the waterfall might 

 be harnessed and made to turn his machinery or to produce 

 electricity. In this mechanical age we frequently forget 

 that only a few thousand years ago there were no machines 

 of any kind. All work that was then performed for man was 

 done by his own hands or by his domestic animals. 



Tremendous progress has been made in the past two or 

 three generations toward applying the discoveries of science 

 to the enriching and conserving of human life. So much has 

 been accomplished in this direction that we may rightly raise 



