288 THE BACTERIOPHAGE AND ITS BEHAVIOR 



calcium carbonate brought about by the addition of a concentrated 

 lactate solution. 



Kabeshima''^* has stated that the bacteriophage is precipitated by 

 alcohol and by acetone. This is true/'* but, contrary to the additional 

 statement of this author, the bacteriophage is very quickly destroyed 

 if the contact is prolonged, either with alcohol or with acetone. We 

 will revert to this point later. 



4. ADSORPTION OF BACTERIOPHAGE CORPUSCLES 



The bacteriophage corpuscle being a negatively charged colloidal 

 micella, at least, when in an alkaline medium, it should be subject 

 to the phenomenon of adsorption. Those who have studied this phase 

 of the question are a long way from being in accord. From what does 

 this disagreement result? Unquestionably two fundamental causes 

 contribute to the difference in opinion. 



A great many bacteriologists who undertake to deal with physico- 

 chemical questions are not too familiar with this science. They forget, 

 for example, that the conditions of the medium, the pH in particular, 

 exert a very definite effect upon colloidal phenomena. We have, for 

 example, studied the phenomena of adsorption with bacteria, and we 

 have found that apparently insignificant differences in the reaction 

 of the medium exercise a great influence on their abiUty to pass through 

 filters. We know, in fact, that filters are permeated by pores whose 

 diameter is far greater than that of the bacteria. If the bacterial cells 

 are retained, it is not because they can not pass through these pores, 

 but because they are adsorbed by the walls. This phenomenon of 

 adsorption is not observed solely with filter candles, but even with the 

 grains of sand which form the filter beds of the commercial filters 

 used for the purification of drinking water. But even here, the passage 

 of bacteria is found to be, in great part, determined by the reaction 

 of the medium. 



The phenomena of adsorption are the more intense as the colloidal 

 properties are the more outspoken, that is to say, as the particles 

 of the colloid become smaller. If granules as voluminous as bacteria 

 are capable of being adsorbed, the adsorption being modified by the 

 reaction of the medium, there is the greater reason that this phenomenon 

 may be more intense with bacteriophage corpuscles whose diameter 

 is but one-twentieth or one-fiftieth as great. 



But there is a second possible cause of error depending on the inherent 

 variability of the bacteriophage, since each race presents its own 



