140 The Story of the Bacteria 



which are called ultra-microscopic, and which 

 no man has really distinctly seen except in 

 masses. 



Whooping-cough and Mumps belong among 

 the milder infective maladies, but their incit- 

 ing agents have not yet been clearly identified. 



There are many other diseases of men and 

 animals incited by bacteria which are of much 

 less importance than those which we have 

 glanced at in our hurried survey. But the 

 limits of this little book do not permit us to 

 dwell upon them. 



