150 PATHOGENIC BACTERIA. 



the suppurative changes in wounds entered the exposed 

 tissues principally from the atmosphere, and that the 

 hands and instruments of the operator, while certainly 

 means of infection, were secondary in importance to it. 



The researches of more recent date, however, have 

 shown not only that the atmosphere cannot be disin- 

 fected, but also that the air of ordinarily quiet rooms, 

 while containing the spores of numerous saprophytic 

 organisms, very rarely contains many pathogenic bac- 

 teria. We now also know that a direct stream of air, 

 such as is generated by an atomizer, causes more bacteria 

 to be conveyed into a wound than would ordinarily fall 

 upon it, thereby increasing instead of lessening the dan- 

 ger of infection. It may therefore be stated, with a 

 reasonable amount of certainty, that the atmosphere is 

 rarely an important factor in the process of suppuration. 



We have already called attention to the fact that 

 various micro-organisms are so intimate in their relation 

 to the skin that it is almost impossible to get rid of them, 

 and have cited in this relation the experiments of Welch, 

 Robb, and Ghriskey, whose method of disinfecting the 

 hands has been recommended as the best. The investi- 

 gations of these observers have shown that, no matter 

 how rigid the disinfection of the patient's skin, the 

 cleansing of the operator's hands, the sterilization of 

 the instruments, and the precautions exercised, a certain 

 number of wounds in which sutures are employed will 

 always suppurate. The cause of the suppuration is a 

 matter of vast importance in surgery and in surgical bac- 

 teriology, yet it is one which it is impossible to remove. 

 We carry it constantly with us upon our skins. 



Welch has described, under the name Staphylococcus 

 epidermidis albus, a micrococcus which seems to be habit- 

 ually present upon the skin, not only upon the surface, 

 but also deep down in the Malpighian layer. He is of 

 the opinion that it is the same organism which is familiar 

 to us under the name of Staphylococcus pyogenes albus, 

 but in an attenuated condition. If his opinion be correct, 



