90 THE BACTERIOPHAGE 



The subcultures on agar can be multiplied but the appearance 

 is always the same, and no matter which of the colonies is selected 

 the biologic tests mentioned above always show that they are 

 related to the original bacterium. Further, the possibility of 

 reversion to the bacillary form in pure culture when grown on a 

 glucose agar medium demonstrates conclusively that contamina- 

 tion has not taken place. 



How may these facts be explained? Early in the consideration 

 of the phenomenon the hypothesis presented itself that in these 

 secondary cultures a visible form of the bacteriophage was pres- 

 ent. But experiment has shown that this interpretation was 

 false. A second idea has developed which unfortunately has not 

 been completely studied for lack of time (the subject of the 

 bacteriophage is so far-reaching that it has seemed more essential 

 to utilize the available time on experiments dealing with the func- 

 tion of the bacteriophage rather than with those of the question 

 of morphology) but is presented only that it may be considered 

 by those who are particularly competent to engage in morphologic 

 studies. 



The necessity of bacterial intervention for the production of 

 asci by certain fungi 7 is a condition clearly recognized in mycology. 

 This same situation may intervene among bacteria which are 

 resistant to parasitism. 8 



This hypothesis is perhaps the less improbable since, according 

 to Schaudinn, sexuality is a fundamental characteristic of living 

 matter. It is observed with B. butschlii and with B. sporonema 

 (in addition to the usual mode of reproduction by transverse 



7 For example, Ascobolus furfuraceus (Moliard, 1903), a fungus of the 

 genus Willia (Sartory, 1902), and an aspergillus growing on the banana 

 (Sartory, 1920). 



8 The following suggests that under the influence of the bacteriophage 

 non-spore-forming bacteria may give rise to filtrable forms. I have 

 noted, although rarely, that a filtrate obtained by passing a secondary 

 culture through a Chamberland bougie (L 2 and even Ls) becomes turbid 

 after some days. Each time that this has been noted the turbidity has 

 been due to the growth of a resistant bacterium such as was present in the 

 secondary culture prior to the filtration. The conditions under which 

 this phenomenon occurs have not been ascertained, thus the observation 

 is simply mentioned without emphasis being placed on its interpretation. 



