INVASION THROUGH THE SKIN 237 



invasion of the particular kinds of bacteria which pass in 

 through the skin. A person whose skin is not broken can 

 without danger handle infectious material which might pro- 

 duce fat^l results were the skin cut or bruised. It is, how- 

 ever, hardly ever the case that a person's skin is unbroken 

 over his entire body. Cuts, bruises, and scratches break 

 the skin, and through such openings microorganisms may 

 find entrance into the body. A little sliver in the skin is 

 frequently the starting point of a fester, a boil, or an 

 abscess, or even of a severe and perhaps fatal case of 

 blood poisoning. So small a thing as a pin prick may 

 sometimes allow entrance to mischievous bacteria. 



The conclusion of all this is that a whole skin is a 

 protection which can almost absolutely be relied upon ; 

 but a more important lesson is that any break in the 

 skin should be more or less carefully protected. The 

 almost surely fatal disease lockjaw (tetanus) comes from 

 soil bacteria getting into the body through the skin, and 

 is apt to occur in wounds made by rusty nails, etc., which 

 have been lying a long time on the earth and have become 

 contaminated with the lockjaw bacillus. All cuts and 

 bruises should be carefully washed with boiled, i.e. steril- 

 ized, water. The fear of bacteria explains why the sur- 

 geon endeavors to clean the surfaces of wounds by some 

 disinfectant which will prevent the growth of micro- 

 organisms. Here, too, is the reason for protecting from 

 further contamination a wound thus cleansed, by covering 

 with bandage or plaster. All of these devices are for the 

 purpose of protecting the body from the entrance of bac- 

 teria, and make it possible for the wound to heal readily 

 without the disturbance which would be produced if 



