The Organisms Which Prey 

 Upon Microorganisms 



Dr. Wallin's discussion of the living nature of mitochon- 

 dria is suggestive of Dr. Felix d'Herelle's studies on the 

 bacteriophage. In 



The Bacteriophage and Its Behavior 



Dr. d'Herelle reviews all the evidence for and against 

 bacteriophagy and summarizes the results of experiments, 

 both his own extensive researches and those of other investi- 

 gators. In it he states, "I offer physiological proof of the 

 living nature of the bacteriophage." It is a comprehen- 

 sive, almost an encyclopedic' volume. The bibliography is 

 a feature. Price $8.00 



Immunity in Natural Infectious Diseases 



Is another of Dr. d'Herelle's studies relating to the bac- 

 teriophage. In it he presents a new concept of the mech- 

 anism of immunity, observed in natural infectious disease, 

 rather than in disease artificially produced in the labora- 

 tory. "A sick animal propagates disease. An animal in a 

 state of active resistance propagates immunity. These few 

 words sum up the whole history of epidemics," the author 

 states. The price of the book is $5.00. 



THE WILLIAMS & WILKINS COMPANY 



Publishers of Scientific Books and Periodicals 



BALTIMORE, U. S. A. 



