238 BACTERIA, YEASTS, AND MOLDS 



bacteria got into the wound. Modern surgery is based on 

 the simple plan of keeping bacteria out of wounds. The 

 frequent efficacy of treating wounds by such crude meth- 

 ods as covering them with tobacco juice or even mud 

 is due to the fact that these act as mild antiseptics and 

 protect wound surfaces from the entrance of dangerous 

 organisms. 



The skin should therefore be carefully guarded, and in 

 all cases of diseases connected with the skin, a list of 

 which has been given above, special care should be taken 

 that no part of the body which is cut or bruised or 

 scratched, or has sores upon the surface, should be 

 allowed to come in contact with infectious material. If 

 this is done, the danger of contagion will be greatly 

 reduced. Though a person with whole skin may safely 

 handle infectious material, no matter how dangerous it is, 

 one whose hands contain even the smallest pin scratch 

 might contract contagion and suffer illness'or death from 

 such procedure. 



The Mouth. Some diseases find entrance through the 

 mouth by means of the food or drink swallowed. They 

 are chiefly typhoid fever, tuberculosis, diphtheria, and cholera, 

 although there are some others. It is manifest that not 

 only is the chance of contagion through the mouth less 

 than when a disease is borne by air currents and enters 

 through the skin, but it is more easily prevented. The 

 diseases mentioned are not usually regarded as very con- 

 tagious, except in the case of diphtheria, where the contagion 

 may be through food (milk) or air. To prevent contagion 

 from most of these diseases it is only necessary to guard 

 all that enters the mouth, keeping it free from infection. 



