744 MOPE OF SPREAD OF INFECTIVE DISEASES. 



Lungs. 



There is no 

 passage of 

 bacteria 

 through the 

 lungs and in- 

 testine. 



invasion of 



troduction of 



bacteria into 



the blood. 



Experiments as to the passability of the surfaces of 

 the lungs were made by causing the animals to inhale 

 either the dried cultivation in the form of dust, or a fluid 

 cultivation in the form of spray; or the material was 

 injected into the trachea in small and repeated quantities. 

 Here also no passage of the bacteria into the blood was 

 observed, even when the lung tissue had undergone 

 pathological changes as the result of the injections. 

 These results harmoniso entirely with those obtained by 

 Arnold, who found by very numerous and careful investi- 

 gations that minute bodies (soot, ultramarine, &c.), when 

 inhaled do not pass into the blood or organs of the body, 

 but at most only reach the neighbouring bronchial glands. 

 Arnold has ascertained by accurate microscopical investi- 

 gations that the human lung does not behave differently 

 to that of animals as regards its passability to minute 

 elements ; soot does not pass into the internal human 

 organs by normal preformed paths, but only by abnormal 

 ways. 



Hence we have given up the former view that bacteria 

 can pass readily into the blood, and from thence into 

 the organs of the body through the intact lungs or the 

 normal intestine ; on the contrary, the body of warm- 

 blooded animals nowhere offers a surface permeable by 

 infective agents, so far as is as yet known, unless im- 

 portant alterations of the normal tissue have previously 

 occurred. 



One mode in which an infective agent can enter the 



r blood and the internal organs of the body is when a 



large opening is present which permits its direct passage 



i i i i * i j t ,1 i 



into the blood ; lor example, a wound 01 the skin or 

 mucous membrane communicating with a blood vessel. 



animals in the follicles of the processus vermiformis and of the 

 sacculus rot. at the entrance to the caecum, which had evidently pene- 

 trated from the lumen of the intestine ; they did not appear to be alive 

 in the deeper layers of the follicles, and could not be traced beyond 

 the follicles. This occurrence of bacteria at one special part of the 

 intestinal mucous membrane, together with the constantly negative 

 results obtained in other parts of the intestine, and with the evident 

 death of these bacteria in the deeper layers, quite corresponds with 

 the results of Wyesokowitsch's experiments. 



