HISTORY OP MICROBIOLOGY 9 



causes of some diseases have not been discovered. Smallpox, scar- 

 let fever, yellow fever, mumps, whooping-cough, epidemic infantile 

 paralysis, hydrophobia, and others offer an inviting field to the medical 

 microbiologist; and the many problems of soil microbiology call for 

 solution by the agricultural microbiologist. Yet it cannot be said that 

 the laborers are few. 



The record of past achievements is an inspiration; and the knowl- 

 edge that each discovery was the result of persistent and concentrated 

 effort, may give us of the present day firmer faith and greater strength 

 for work in the broad and inviting field before us. 



