64 Lectures on Bacteria. [jj vii. 



tion of the objects intended to be protected from the Bacteria. 

 We must therefore be content with what is within our reach. 



If, as there is no reason to doubt, the favourable results of the 

 application of disinfectants at the present day, the splendid 

 results of antisepsis in surgery, are due to the protection obtained 

 against destructive Bacteria, there can be at the same time little 

 doubt that this protection, partly due to the absence of germs 

 through the increase of cleanliness consequent on these modes 

 of procedure, is chiefly secured by staying the development of 

 the germs and in a much less degree by their destruction. The 

 elaborate experiments of Koch (14, p. 234) show that of the 

 various disinfecting and antiseptic agents in the proper state of 

 concentration or dilution, only corrosive sublimate, chlorine and 

 bromine have the effect of killing the germs. Bodies like 

 salicylic, carbolic, and other acids in the suitable state of 

 dilution, and powdered cane-sugar can only be supposed to have 

 the desired effect by stopping the growth of the Bacteria. It 

 wou^d be highly important to enquire more closely into the 

 specific sensibilities which may exist in the different species of 

 Bacteria. The behaviour of a Micrococcus of ulcer or erysipelas 

 in the presence of antiseptics may possibly be different from that 

 of Bacillus Anthracis, which has been the chief subject of Koch's 

 study. 



VII. 



Relation to and effect upon the substratum. Sapro- 

 phytes and Parasites. Saprophytes as exciting 

 decompositions and fermentations. Characteristic 

 qualities of Forms exciting fermentation. 



THE vegetative process in organisms, which use organic com- 

 pounds for their food, must necessarily effect changes in the 

 substratum from which this food is withdrawn. To these 

 changes are added other effects, more closely connected with 

 the process of respiration, which lead to profound transforma- 

 tions in the organic substratum. 



