Aug. 19, 19221 THE BACTERIOPHAGE. [ McIrcAf JoukLl 



These researches seem to indicate another possible explanation of the lytic 

 action of the substance under review. If this substance is, after all, not patho- 

 logical to the bacterium, but is a normal product of its activity, then it must 

 be produced for some special purpose w^hich is advantageous to the life of 

 that variety of bacterium. If the "special forms" of bacilli which are found in 

 normal cultures and are so soon dissolved up are produced for the benefit of 

 the bacterial community of a pure culture, then it may be that the lytic agent 

 is formed for the purpose of carrying out this lytic action, and possibly setting 

 free toxins contained in the special forms. Or it may be that it sets free "anti- 

 toxins," or substances that will neutralize the toxic substances of the host it 

 infects, or such substances as are produced by other varieties of bacteria with 

 which it struggles for existence when outside the animal body. Probably all 

 bacteria produce substances of a toxic nature, but the possibility of their pro- 

 ducing antibodies which will neutralize the toxins of other varieties is one that 

 has interested me for some time. My experiments in this direction lead me to 

 believe that this may be the case, but a research of this nature is rather difficult 

 to carry out technically, and I shall do many more experiments before com- 

 mitting myself to this view. If, however, additional experiments should con- 

 firm my opinion, and if the special forms play some part in this process, one 

 can quite understand that the special forms would be useless among the mem- 

 bers of a pure culture growing on artificial media. In fact, they might be 

 directly detrimental to the bacterial community, in that they would use up 

 the food supply and overgrow the other bacilli which are necessary for a con- 

 tinuation of the life of that species or variety. In this case the lytic agent would 

 perform a good purpose in getting rid of the useless special forms. It may be 

 argued that this will not explain the lysis of the normal forms of bacilli, but 

 then the conditions of cultivation on artificial media are not those of nature. 

 In fact, in the process of evolution the bacterium did not develop its characters 

 under the influence of cultivation in incubators, and an action that might be 

 restrained to the limits of useful purposes in nature might very well extend 

 beyond those limits under such an abnormal environment as that presented 

 by an uncontaminated tube of agar. 



Some of my views and the possibilities I have suggested are no doubt open 

 to criticism, but I claim that the discovery of the filter-passing lytic agent in 

 association with bacteria offers a large field for research, and I suggest that 

 this field has been further extended by the isolation of "special forms" of bac- 

 teria and by the possibility of demonstrating the production of bacterial anti- 

 toxins for the neutralization of toxins produced by other varieties of bacteria. 

 Moreover, it must be remembered that all the vital processes of a bacterium 

 have some relation to each other, and it is therefore necessary to study these 

 problems together, or the true significance of any one may not be fully appre- 

 ciated. 



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