CHAPTER IV. 

 THE BACTERIA OF THE NORMAL HUMAN BODY. 



Although there is considerable discrepancy in the results of 

 various investigations in regard to the matter, it would appear 

 that the solid tissues of the animal body, the blood and lymph, 

 and the cavities that have no connection with the outer world, 

 are often free from bacteria.* So also the maxillary, eth- 

 moidal and frontal sinuses, middle ear,t urinary bladder, 

 uterus and Fallopian tubes, and to a less extent the lungs J and 

 gall-bladder, § although having external connections, are 

 usually sterile when in a healthy condition. When bacteria do 

 enter the tissues from any of the surfaces their progress is 

 checked by means of the activities of the cells or fluids of the 

 body, and if they succeed in penetrating to any considerable 

 distance their advance is usually arrested by the nearest group 

 of lymph-nodes, which appear to be important safeguards for 

 preventing the dissemination of bacteria throughout the body. 

 As a rule, the sections of the mucous membranes are inimical 

 to bacteria. 



The skin, 1 1 as might be expected, is liable to have upon it 



*Ford found small numbers of bacteria in the normal organs of rabbits, cats 

 and dogs in the majority of those examined. The species of bacteria obtained 

 were mostly common saprophytes, and to some extent constant in the same 

 kind of animal. Journal of Hygiene. Vol. I. 1901. 



tCalamida and Bertarelli. Centralblaii jur Bakienologie. Vol. XXXII. igo2. 

 Orig. p. 428. Torne. Ibidem. XXXJII. 1903. p. 250. Hasslauer. 

 Ibidem. Referate. XXXII, p. 174. An examination of these articles will 

 show that investigators disagree somewhat, with regard to the sterility cf these 

 cavities. 



tSee Wadsworth. American Journal Medical Sciences. May, 1004. 



§See Bacteriology of the Gall-bladder and its Ducts. American Journal 

 Medical Sciences. Vol. CXXIII., p. 372. 



llSabouraud. La Peau Humaine, etc. Bulletin de V Instilut Pasteur. II 

 1904. Pages 233, 282. 



160 



