NATURE OF BACTERIOPHAGE 349 



amine (also performed by Prausnitz and Firle). They made 23 passages 

 in media containing higher and higher concentrations of chloramine. 

 They then spread the suspension on agar in order to secure isolated 

 plaques, and separated these plaques for the following passage. 



In the table covering their findings (table 39) the results show the 

 outcome when suspensions of the bacteriophage derived from these 

 different plaques were added to equal quantities of chloramine solution. 



Adaptation to chloramine is acquired with greater difficulty than is 

 that to phenol, and especially, that to mercuric chloride. The resist- 

 ance of the corpuscles from Plaque No. 3 is, however, very appreciable, 

 as the authors of this extremely interesting series of experiments have 

 observed. 



Considered as a whole, these experiments show, beyond doubt, that 

 the bacteriophage corpuscle is capable of adapting itself to the condi- 

 tions of the moment. 



6. THE FACULTY OF MULTIPLICATION OF THE BACTERIOPHAGE 

 CORPUSCLE 



Each of the two fundamental characteristics of living beings has a 

 consequent phenomenon, which, always found in association with the 

 basic character, forms to it a sort of corollary. For assimilation this 

 corollary is the faculty of multiplication ; for adaptation, the capacity for 

 the characters of a single being to vary at different times, which in its 

 turn necessarily involves a variability between beings belonging to the 

 same species. 



The power of assimilation has, then, for a corollary, the faculty of 

 multiplication, a faculty which is exercised when the conditions are 

 favorable, that is, when assimilation can take place freely. This is true, 

 however, whether the assimilation takes place in a heterologous or in a 

 homologous medium, for the crystal immersed in a concentrated solu- 

 tion of the homologous material multiplies Just as surely as does another 

 being endowed with the power to assimilate in a heterologous medium 

 providing it with assimilable substances.* 



To consider more specifically the beings of the latter class, those cap- 

 able of assimilating heterologous substances, we find that the elementary 

 mass, when the being is immersed in a medium containing assimilable 

 substances, tends to increase indefinitely, until the assimilable materials 

 are exhausted, if we disregard, naturally, such limiting processes as the 

 accumulation of waste materials. But in all beings endowed with this 



* This clearly shows that multiplication is simply a corollary of assimilation. 



