DISINFECTION OF THE TISSUES 87 



even where most abundant, is in such minute quantities as to be quite 

 without influence. 



The fact that thousands of bacteria pass through our digestive organs 

 every day suggests the question whether any of the digestive secretions 

 function as natural disinfectants. The saliva and the pancreatic juice are 

 alkaline in reaction and unable to injure bacteria. The pancreatic juice, by 

 reason of the proteids it contains, is even nutritious. The bile acids 

 inhibit the growth of bacteria, but of all the digestive secretions the free 

 acid of the gastric juice (2-3 per thousand H CI) alone is able to kill them. 

 The action of this even is in any case uncertain, and can only affect sporeless 

 cells. Normal gastric juice in a test tube destroys in half an hour the 

 bacteria of cholera, typhoid and glanders, pus cocci, and the sporeless cells 

 of anthrax and tetanus (57), but spores are not injured by passing through the 

 stomach. To destroy anthrax spores, they must lie for six hours in 2 per 

 cent. H CI, so that it is evident the gastric secretion with only from -a to 

 •3 per cent. H CI is quite inadequate, even if allowed to act for days. 

 Even against sporeless bacteria it is of little effect, as the examples quoted 

 show. Bacteria given to animals in their food (B. pyocyaneus, blood in- 

 fected with anthrax, tuberculous tissues) are not entirely destroyed even after 

 six or eight hours (58). 



Chemical disinfection of the diseased body is not possible, for the tissue 

 cells would be just as much injured by the disinfectant as the bacteria. 

 Nor is it possible to disinfect by chemical means wounds in which bacteria 

 have taken up their abode ; an antisepsis of wounds is not possible. When 

 a wound cannot be purified by mechanical means the body must be helped 

 to fight against the invaders, and the only way to do this is to secure clean- 

 liness, asepsis. Asepsis confines itself to the treatment of wounds with 

 germ-free instruments and dressings without using chemical disinfectants, 

 and is sufficient to prevent clean fresh wounds, such as are made at 

 operations, from becoming infected. 



As to the cause of the fatal action of disinfectants upon the bacteria we 

 know but little. We know that the salts of the heavy metals, corrosive 

 sublimate or nitrate of silver for instance, coagulate protoplasm. They 

 destroy life probably by precipitating certain substances from the extremely 

 complex protoplasm of the cells. Other compounds, such as alkalies and 

 acids, may perhaps act by the separation and solution of proteid bodies, 

 resulting in a destruction of the protoplasmic structure. Even a change 

 in reaction might cause the precipitation of certain constituents. In most 

 cases, however, the matter is beyond any explanation, because we have no 

 knowledge of the peculiarities of protoplasmic structure on which the 

 phenomena of life depend. 



