50 THE BACTERIOPHAGE AND ITS BEHAVIOR 



relationships, such as may be provided by varying within a given 

 medium the proportions of the two antagonists involved, the bacterio- 

 phage principle and the bacterium to which it is opposed. 



It must be recalled that in these first chapters we are dealing only 

 with extremely active bacteriophage principles, that is to say, with 

 those capable of completely and 'permanently dissolving all of the bacteria 

 present in a medium, even though only an infinitely small quantity of 

 the filtrate containing the bacteriophage principle (a millionth of a 

 cubic centimeter, or less) is introduced into a definitely turbid sus- 

 pension of bacteria. 



Into a constant quantity of medium, or peptone broth with a pH 

 of 7.8, we may introduce, either a very few bacteria (as about one to 

 each centimeter) or a very great number (several biUions). On the 

 other hand, whatever the number of bacteria, we may inoculate the 

 suspension with a very minute quantity of a filtrate containing the 

 bacteriophage principle, as 0.000,000,000,1, or IQ-^^ cc* or with a con- 

 siderable quantity, as 1 cc, or, indeed, with any intermediate amount. 



Many of the experiments which I have published dealing with the 

 effect of the relative concentrations in the medium of bacteria and bac- 

 teriophage in their bearing upon the nature and course of the phenom- 

 enon of bacteriophagy, have been repeated by many investigators, 

 and in all cases their observations have been comparable to mine. It 

 could hardly be otherwise; the facts are so clear-cut that doubt is 

 impossible. As for the deductions inspired by these facts, questions 

 bearing upon the mode of regeneration of the active principle, for 



* Throughout the text the logarithmic notation, the most convenient for ex- 

 pressing such values, will be utilized. Despite the fact that this notation has 

 been rather widely employed in recent publications, it may be unfamiliar to some. 

 The following table of equivalents is therefore provided. 



10-1 =0.1 cc. (a tenth of a cubic centimeter) 



10-2 — 0.01 cc. (a hundredth of a cubic centimeter), etc. 



10-3 = 0.001 cc. 



10-" = 0.000,1 cc. 



10-5 = 0.000,01 cc. 



10-« = 0.000,001 cc. 



10-^ = 0.000,000,1 cc. 



10-8 = 0.000,000,01 cc. 



10-9 = 0.000,000,001 cc. 



10-1" = 0.000,000,000,1 cc. (a ten-billionth part of a cubic centimeter) 

 In brief, the negative exponent represents the number of figures at the right 

 of the decimal point. It is likewise the characteristic of the log of the decimal 

 fractional number expressing the quantity of liquid. 



