VII] CHEMISTRY OF BACTERIA 133 



(J to ;| of a culture) into the peritoneal cavity of guinea- 

 pigs — highly susceptible to this microbe when subcutaneously 

 injected — without producing disease or death. 



Injecting, then, the bacilli of a particular species, dead or 

 living, in fair quantities into the peritoneal cavity, and pro- 

 ducing thereby disease and death, does not prove in the least 

 that this species is, strictly speaking, pathogenic, since some 

 notoriously non-pathogenic bacteria (bacillus prodigiosus, 

 vibrio of Tinkler, bacillus subtilis) do the same, while some 

 notoriously specific bacteria (bacillus of fowl cholera — sterile ; 

 bacillus diptherise — living or dead; and bacillus anthracis — 

 dead) do not produce such a result. All that can be said 

 in such cases is that the bacillary bodies do or do not 

 contain the intracellular poison that causes fatal peritonitis, 

 or contain it in small amount, or contain it very abundantly. 

 Whether a given species is or is not pathogenic — can or cannot 

 produce in the natural or artificial culture media specific 

 toxins — is a question totally separate from the above. Voges 

 separated by watery extract from growths of bacillus pro- 

 digiosus a substance which causes on injection a temporary 

 rise of temperature in guinea-pigs ; this is evidently a sub- 

 stance distinct from the intracellular poisons that cause the 

 above-mentioned fall of temperature and fatal peritonitis. 



The intracellular poisons present in many, absent in 

 some, species of bacteria are thus of a distinctly different 

 order from the specific toxins elaborated by pathogenic 

 bacteria : the former are present in the bacillary bodies as 

 such, no matter whether dead or living ; the latter are the 

 products of metabolism, i.e. results of chemical changes 

 induced in the culture media by the growth and multiplica- 

 tion of the specific bacteria. Any specific change that the 

 living body undergoes, any specific reaction that it is 

 capable of acquiring after the growth in it of the living 



