4 BACTERIOPHAGES 



most cases results were equivocal or disappointing but in certain 

 diseases such as cholera there was some evidence for a favorable 

 effect of phage therapy. Interest in this application has largely 

 subsided since the introduction of the more convenient chemo- 

 therapeutic agents. The early hopes of effective medical use 

 stimulated much valuable work on host range, immunological 

 properties, stability and variation, and other attributes of bac- 

 teriophages. Many of the well-known names in bacteriology 

 and immunology are found in the phage literature of this 

 period: J. Bordet, Costa Cruz, Doerr, A. Fleming, Hauduroy, 

 Levaditi, Prausnitz, and Topley. Also during this period a few 

 men made phage research their life work. Included in this 

 group besides d'Herelle are Asheshov, Bronfenbrenner, Flu, 

 Gratia, and the elder Wollmans. These scientists were inter- 

 ested in the biology of bacteriophages as well as in possible ap- 

 plications and made many contributions of fundamental impor- 

 tance. During the second decade of phage history appear a few 

 men whose work combined biological "feeling" and quantitative 

 methods in the modern manner: Burnet, M. Schlesinger, and 

 C. H. Andrewes. The contributions of these older phage workers 

 and of a very large contemporary school form the subject matter 

 of this book. 



3. Nature of Bacteriophages 



In his original publication, Twort (1915) considered the na- 

 ture of his as yet unnamed lytic agent, asking if it was similar to 

 bacteria, protozoa, or to the filterable viruses; whether it was a 

 filterable stage in the life cycle of the micrococcus affected ; or 

 whether perhaps it was a bacterial enzyme, produced autocatalyt- 

 ically while destroying the bacterium that produced it. A 

 much more elaborate series of hypotheses is discussed in 

 d'Herelle's book (1926). Of these hypotheses two only have 

 survived to the present: the "precursor" theory and the 

 "virus" theory. An active controversy between the proponents 

 of these two theories continued for many years and stimulated 

 much experimental work as well as verbiage. 



