344 BACTERIA. 



is sometimes found that sputum inoculated into mice or 

 rabbits causes their death in a comparatively short period, 

 bacteria being found in their blood ; this blood inoculated into 

 another animal produces a similar disease, such as acute or 

 chronic abscess formation, which may be carried on from 

 generation to generation by simply inoculating a healthy 

 animal with the contents of the abscess. In these cases, 

 however, the organisms that are cultivated from the blood or 

 the pus fail to produce any symptoms at all, and it must be 

 concluded (until further evidence is obtained) that the patho- 

 genic organisms cannot live on the artificial culture media, 

 those that survive on these media being non-pathogenic. 1 

 There are, however, certain pathogenic organisms found in 

 the mouth which can be readily enough cultivated, the first, 

 and one of the most important of which is the micrococcus 

 of sputum septicaemia, which may be grown on blood serum 

 or agar-agar at the temperature of the body ; it grows as a 

 transparent greyish-white gelatinous coating on the surface of 

 the nutrient medium, and looks almost like a dewdrop. It 

 is encapsuled like the pneumococcus described by Friedlander, 

 and usually occurs in sputum in the form of single or paired 

 cocci ; it is found almost invariably in patients suffering 

 from pneumonia, but it also occurs frequently in the mouths 

 of healthy persons. When injected into animals, either 

 in the sputum or as a pure cultivation, death usually occurs in 

 from twenty-four to thirty-six hours ; numerous capsuled 

 cocci are found in the blood, the spleen is enlarged and con- 

 tains a number of organisms ; the symptoms, in fact, are 

 those of an acute septicaemia. It has been observed, 

 however, that pigeons and dogs are unaffected by this dis- 

 ease, whilst rabbits and mice are almost invariably killed 

 by its inoculation. It would appear that when it makes 

 its way from the mouth to the healthy lung this organism 

 has little or no power of attacking the tissues, but that 

 if there be slight congestion or inflammation, just as in 

 the case of inflammation of the gums around the teeth, this 

 organism, finding its way from the mouth (where it may have 

 existed for some time without giving any evidence of its 

 presence) into the air vesicles, is enabled to grow on the 

 exuded fluid constituents of the blood, and to set up at once 



1 Another explanation of this will be found in the chapter on 

 Leprosy. 



