400 



Microbes and You 



#fc 



^^. 



Fig. 74. Bacteriophage action on cells of Escherichia coli X 25,000. 

 (A) Phage particles adsorbed to bacteria. (B) Invasion and disintegra- 

 tion of bacterium after 23 minutes exposure. {From S. E. Luria, M. 

 Delbriick, and T. F. Anderson, Journal of Bacteriology, 1943, 46, 57-58. 

 Photographs kindly furnished by C.J. Witton.) 



ture suspension of the dysentery organisms, lysis of the bacteria 

 occurred. He termed this transmissible agent bacteriophage. 

 The digestive tract of man and lower animals is the apparent 

 natural habitat of these bacterial parasites. Bacteriophages range 

 in size from about 10 to 75 millimicrons, and electron microscope 

 studies reveal them to be round or tadpole shaped. 



Phage has at various times through the years been considered 



