Bacteriolytic Element found in Tissues and Secretions. 317 



certain tissues to certain infections, or conversely the well-known predilection 

 of certain infections for certain tissues. 



The view has been generally held that the function of tears, saliva and 

 sputum, so far as infections are concerned, was to rid the body of microbes 

 by mechanically washing them away. Metchnikoff in his treatise on 

 " Immunity and Infectious Disease," expresses himself very clearly and 

 precisely on this point. From the experiments detailed above, however, 

 it is quite clear that these secretions, together with most of the tissues of 

 the body, have the property of destroying microbes to a very high degree. 



It has not been possible to test extracts of all the different tissues to each 

 of many microbes, but it has been shown that human tears and sputum 

 can dissolve the majority of the microbes (presumably non-pathogenic) 

 recovered from the air of the laboratory. Most of these air-borne bacteria 

 are non-pathogenic, and it seems extremely unlikely that they could 

 become pathogenic when the human secretions show such a destructive action 

 towards them. 



Again, the human secretions showed lytic power to most of the microbes 

 tested which, although pathogenic to some animals are harmless to man. 

 Notably there was a certain amount of lysis evident with the bacillus abortus 

 of Bang and B. pseudotuberculosis rodentium, which are culturally and 

 serologically identical with M. melitensis and B. r pestis respectively, both of 

 which latter organisms are very pathogenic for man, and for which there is 

 apparently no lysozyme in the human secretions. It may be that it is 

 in this sensitiveness to a human lysozyme that the difference between these 

 microbes lies. 



DESCRIPTION OF PLATE. 

 Fig. 1. — Photograph of agar plate with imbedded tears. 



.Fig. 2. — Bactericidal power of tears on streptococci. Upper half — culture from 

 streptococci in salt solution. Lower half — culture from same number of 

 streptococci in tears (1 in 100). 



Fig. 3. — Upper half — Micrococci's lysodeikticus before being acted on by tears. Lower 

 half — same partially dissolved by tears. Examined by Burri's method. 



