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 fatal 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 



