mmunity of the skin and mucous membranes 411 



it prevents the multiplication of micro-organisms. F. Klemperer, 

 denies the bactericidal property of the nasal mucus. He could never 

 demonstrate the destruction of micro-organisms by the mucus, and 

 he also observed that bacteria do not multiply at all readily in this 

 medium. These results confirm the hypothesis that the defensive [43 1] 

 action of the nasal mucous membrane against microbial invasion 

 is mainly effected by the mechanical elimination of the numerous 

 micro-organisms which continually reach it. Amongst these orga- 

 nisms are some which are conspicuous for the ease with which 

 they multiply in the body, taking the nasal cavity as a starting point, 

 e.g. the micro-organisms of influenza, the plague bacillus, which, 

 according to several observers, is very virulent when introduced by 

 the nostrils^, and the leprosy bacillus. This last, according to 

 Goldschmidt^, Sticker*, and Jeanselme^ often enters the human body 

 by way of the nose. 



It is certain that the olfactory apparatus deprives the inspired air 

 of a large number of the micro-organisms which it carries. These 

 organisms deposited on the mucous membrane are expelled with the 

 nasal mucus. A number of the foreign organisms, carried by the air, 

 may, however, surmount this first barrier and penetrate further into 

 the trachea and bronchi, whence, helped by the movements of the 

 vibratile cilia, they are usually expelled along with the mucus. 



In spite of this double defence it has been recognised that very 

 minute corpuscles and, amongst others, micro-organisms may over- 

 come every one of these obstacles and reach the pulmonary alveoli. 

 Here, under the name of " dust-cells '' ("cellules k poussifere")— 

 " Staubzellen " of the German writers— located in the alveoli, are de- 

 scribed certain large mononucleated elements which contain granules 

 of foreign origin, usually deposits of soot, of a deep black. This 

 permeability of the normal lung tissue for dust particles and pig- 

 mented corpuscles has been closely studied and clearly demonstrated 

 by J. Arnold^ and his pupils. Several observers have tried to 

 determine whether micro-organisms, introduced by the respiratory 



1 Miinchen. med. JVchnschr., 1896, S. 730. 



2 BatzaroflF, "La pneumonie pesteuse experimentale," Ann. de VImt. Pasteur, 

 Paris, 1899, t. xiii, p. 385. 



3 " La Lepre," Paris, 1894. 



* Munchen. med. Wchnschr., 1897, S. 1063. 

 ^ Presse med., Paris, 1899, 8 avril. 



* " Untersuchungen uber Staubinhalation," Leipzig, 1885. 



