3/0 BACTERIOLOGY. 



rophytes and also with parasites and their 

 poisons. This power is in itself nothing pe- 

 culiarly " specific," bnt only specific to the ex- 

 tent that we are in general able to distinguish 

 species and races, organs and tissues. In this 

 general sense some species of microbes are able 

 to enter into close relations with man, while 

 others only sustain relations more remote and 

 others none at all. Seemingly qualitative 

 deviations are often only quantitative modifi- 

 cations of some of the" fundamental activities 

 that are common to all cells. The qualitative 

 aspect is at bottom merely due to an accom- 

 modation of our ideas to the subjective limits 

 of our knowledge just as we anthropocentric- 

 ally distinguish light and electricity, tubercu- 

 losis and diphtheria, without ' any intrinsic 

 necessity. If this is kept in mind there can 

 be no great harm in asserting that the natural 

 resistance of man to disease-producing bacteria 

 has a " specific " character, that it exists as a 

 natural endowment protecting against certain 

 species of parasites and not against others. It 

 is another expression, a different statement of 

 the well-known fact. 



As compared with this condition, " speci- 

 fic " immunization presents further problems. 

 Metschnikoff has found that before animals 

 have received a protective inoculation against 



