324 THE BACTEEIOPHAGE AND ITS BEHAVIOR 



cultures grown at 10°C. were free of the bacteriophage he heated them 

 at 58°C., and as he was unable to reveal a bacteriophage after such 

 treatment he concluded that it was not present. Such an assumption 

 is not valid. In an earher chapter some experiments have been detailed 

 which show that the bacteriophage is attenuated at even lower tempera- 

 tures than 58°C. I would state once more that any method of isolation 

 involving heating should never be used in important experiments if one 

 wishes to avoid a very important source of error. Flu has informed me 

 that he has repeated Gildemeister's experiments with the same strain 

 of B. coli, (sent to him by Gildemeister) obtaining quite different results. 

 His technic, however, differed for he used filtration in the place of heat, 

 for isolating the bacteriophage. He found that after a series of ten 

 successive cultivations at 10°C. the filtrate prepared from the last cul- 

 ture contained a bacteriophage. Obviously this renders the conclusion 

 of Gildemeister subject to revision. ^Vhat happened in the original 

 experiments was that by growth at 10°C. an attenuation occurred, so 

 that the bacteriophage became completely avirulent when heated to 

 58°C. 



The only thing disclosed by Gildemeister's experiments is that the 

 bacteriophage, which as we know undergoes an attentuation when cul- 

 tivated at high temperatures, is also attenuated when grown at a low 

 temperature. 



And finally, in order to finish with this question, it may be stated that 

 some of the supporters of the autolysin hypotheses have, as a matter of 

 fact, reahzed that they are inadequate to explain the facts, for bacteri- 

 ophagy has no single character in common with autolysis. Thus, Otto 

 and Munter'*^" have suggested that the normal autolysin may be 

 enhanced by passage through filters of porcelain or by heating. This 

 again is an explanation which does not conform to the facts, for with a 

 bacteriophage of maximum virulence, bacteriophagy takes place with- 

 out the subsequent development of secondary cultures, and with such a 

 race it is possible to continue serial bacteriophagy indefinitely, inoculat- 

 ing each fresh bacterial suspension with a trace of the suspension pre- 

 viously bacteriophaged, without ever bringing the active principle in 

 contact with a filter and without ever subjecting it to heat. 



Experiment shows, therefore, that the principle responsible for bac- 

 teriophagy is not a constituent of normal bacilli ; hence it can not be an 

 autolysin. Does an autolysin play any part in the phenomenon? This 

 is quite possible. But however that may be, the principle which 

 is the essence of the phenomenon, which assures the continuity in 



