142 THE TOXINES PRODUCED BY BACTERIA. 



one hand, and to the medium in which the latter may be 

 growing is a subject which has received considerable atten- 

 tion, and intracellular as distinguished from extracellular 

 poisons have been spoken of. The main difference be- 

 tween such depends on whether a poison is or is not easily 

 diffusible into the artificial or natural food medium of the 

 bacterium, though of course if Martin's view on the forma- 

 tion of toxic albumoses by digestion is correct, these 

 latter not only exist extracellularly, but are also probably 

 formed outside the cell. Great differences exist in the 

 diffusibility of bacterial poisons into artificial media. Thus 

 both with the B. diphtherias and the B. tetani a filtered 

 bacteria-free bouillon culture is very toxic. A bouillon 

 culture, similarly treated, from the B. anthracis is relatively 

 non-toxic, and Pfeiffer found the same to be true of the 

 vibrio of Massowah (one of the cholera group). There is 

 evidence that not only poisons injured by heat but those 

 uninjured by heat may exist intracellularly. Thus, if the 

 bodies of tubercle bacilli killed by heat be injected into an 

 animal, tubercular nodules are formed round them, from 

 which it is inferred that they must have contained charac- 

 teristic toxines, seeing that characteristic lesions result. The 

 bodies of the cholera vibrio are also similarly toxic. Too 

 much stress must not, however, be laid upon the difference 

 between intracellular and extracellular poisons, for as a 

 matter of practice in any medium derived from bacteria 

 both must be present. In a bouillon culture of a bacterium 

 containing non-diffusible toxines the death of great numbers 

 of bacteria, which is constantly taking place in every culture, 

 results in the disintegration of their bodies and the passing 

 of the material they contained into the culture fluid. On 

 the other hand, a scraping from the surface of say an agar 

 culture of a bacterium forming diffusible toxines will 

 necessarily contain these toxines from the fact that a certain 

 quantity of free fluid will always be present. 



Summary. To sum up our knowledge of this subject. 

 The word toxine is a very general term, and the bodies to 

 which it is at present applied are probably of different 



