THE BACTERIA OF THE NORMAL HUMAN BODY. 



CHAPTER IV. 



THE BACTERIA OF THE NORMAL HUMAN BODY. 



THE numerous solid tissues and organs of the human 

 body, the fluids circulating in the interior like the blood 

 and lymph, and the cavities that have no connection with 

 the outer world, are entirely free from bacteria. 1 So also 

 the maxillary, ethmoidal and frontal sinuses, middle ear, 2 

 urinary bladder, uterus and Fallopian tubes, and to a less 

 extent the lungs and gall-bladder, 3 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 secretions of 

 the mucous membranes are inimical to bacteria. 



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

 it numerous bacteria, especially micrococci, and moulds. 



1 This view is not upheld by the experiments of Ford, who 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. 



2 Calamida and Bertarelli, Centralblatt f. Bakteriologie, Vol. XXXII., 

 1902, Orig. p. 428. Torne, Ibidem, XXXIII., 1903, p. 250. Hasslauer, 

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

 show that investigators disagree somewhat, with regard to the sterility 

 of these cavities. 



3 See Review on the " Bacteriology of the Gall-Bladder and its Ducts," 

 American Journal Medical Sciences, Vol. 123, p. 372. 



