76 Infection 



The intervening acidity of the vagina makes it difi&cult for bacteria 

 from the surface to penetrate so deeply, and the tenacious alkaline 

 mucus of the cervix is an additional barrier to their progress. 

 Careful studies^ of the bacteriology of the uterine secretions have 

 been made by Gottschalk and Immerwahr* and Doderlein and 

 Winterintz.f 



The urethra harbors a few cocci which enter the meatus from the 

 surface and remain local in distribution. 



The normal bladder is free from bacteria. 



The nose constantly receives enormous numbers of bacteria in the 

 dust of the inspired atmosphere. These organisms are too numer- 

 ous and too various to enumerate, and might, indeed, comprehend 

 the entire bacterial flora. But in spite of the large numbers of organ- 

 isms received, the nose retains ^scarcely any, its mucous membranes 

 seeming to be provided with means of disposing of the organisms. 

 Among those best able to withstand the destructive influences, and, 

 therefore, most apt to be found in the deeper passages, are the pseudo- 

 diphtheria bacillus, streptococci, pneumococci, staphylococci. Ba- 

 cillus pneumoniae (Friedlander), Bacillus subtiUs and sarcina. A 

 complete review of the subject with references to the literature has 

 been made by Hasslauer.J 



The larynx and trachea contain very few bacteria and probably 

 have no permanent parasitic flora. 



The lungs harbor no bacteria. A few micro-organisms doubtless 

 reach them in the inspired air, but the defensive mechanisms soon 

 dispose of them. 



AVENUES OF INFECTION 



The skin seems to form an effectual barrier against the entrance 

 of bacteria into the deeper tissues. A iejw higher fungi — Tryco- 

 phyton, Microsporon, Achorion, etc. — seem able to establish them- 

 selves in the superficial layers of the cells, invade the hair-follicles, 

 and so reach the deeper layers, wJhere morbid changes are produced. 

 The minute size of the bacteria makes it possible for them to enter 

 through lesions too small to be noticed. Garre applied a pure 

 culture of Staphylococcus pyogenes aureus to the skin of his fore- 

 arm, and found that furuncles developed in four days, though the 

 skin was supposed to be uninjured. Bockhart moistened his skin 

 with a suspension of the same organism, gently scratphed it with 

 his finger-nail, and suffered from a furuncle some days later. 



The greater number of surgical infections result from the entrance 

 of bacteria through lesions of the skin. It makes but Uttle difference 

 to^what depth the lesion extends— abrasions, punctures, lacerations, 

 incisions — the protective covering is gone and the infecting organ- 



* Ibid., 1896, Bd. L, Heft 3. 



t "Beitrage fur Geburtshulfe und Gynakologie," Bd. ra, Heft 2. 



t "Centralbl. f. Bakt. u. Parasitenk. I. Abt. Referata," Bd. xxxvn, Nos. 1-3, 

 p. I, and Nos. 4-6, p. 97. 



