CHAPTER X. 



THE DESTRUCTION OF BACTERIA BY THE CHEMICALS. 



MANY chemical substances when brought in contact 

 with bacteria unite with their cell substance. New 

 compounds are thus formed, and the life of the bacteria 

 and the disinfecting properties of the substances are usu- 

 ally destroyed. While in the vegetative stage bacteria 

 are much more easily killed than when in the spore 

 form, and their life processes are inhibited by substances 

 less deleterious than those required to destroy them. 



Bacteria both in the vegetative and in the spore 

 form differ among themselves considerably in their 

 resistance to the poisonous effects of chemicals. The 

 reason for this is not as yet clear, but is apparently 

 connected with the structure and chemical nature of 

 their cell substance. 



Chemicals are more poisonous at fairly high than at 

 a low temperature, and act more quickly upon bacteria 

 when they are suspended in fluids singly than when in 

 clumps. The increased energy of disinfectants at higher 

 temperatures indicates in itself a probability that a true 

 chemical reaction takes place. In estimating the ex- 

 tent of the destructive action of chemicals the follow- 

 ing degrees are usually distinguished: 



1. The growth is not permanently interfered with, 

 but the pathogenic and zymogenic functions of the 

 organism are diminished attenuation. 



2. The organisms are not able to multiply, but they 

 are not destroyed by antiseptic action. 



