BACTERIOLOGY. 53 



point for an hour or longer. Likewise, while a three 

 to five per cent solution of carbolic acid kills most bac- 

 teria in half an hour, there are spores that can live for 

 days in the same strength of this acid. 



Obviously, therefore, the sporulating bacteria are of 

 very great importance. Happily the number of sporu- 

 lating bacteria is small, a fact which lessens the difii- 

 culty in disinfection, once these species are known. 

 The principal sporogenous (spore-producing) bac- 

 teria are the tetanus bacillus, the anthrax bacillus, the 

 bacillus of malignant edema, the bacillus aerogenes 

 capsulatus, and probably, the actinomyces bovis and 

 Madurae. Fortunately, not one of these bacteria is the 

 agent of a pestilential, epidemic disease. 



FACTORS NECESSARY TO THE GROWTH OF BACTERIA. 



The factors necessary to the growth of pathogenic 

 bacteria are deserving of as much attention as the 

 means devised for destroying them; indeed, all methods 

 which aim at destroying them (disinfection) must 

 needs be faulty unless attention is paid to the conditions 

 under which they flourish. The means are not always 

 at hand to employ those chemical and physical agents 

 that experience has taught may entirely be relied upon. 

 Nor if they are, do the exigencies of the case, on account 

 of the destructive action on fabrics of the most eflicient 

 disinfectants, or the bulk of the material to be disin- 

 fected, permit of their use. Furthermore, dissemina- 



