/ rjflfr 



V 



192 ACUTE PNEUMONIA. 



(Fig. 52). After a few days' growth they lose their regular 

 shape and size, and involution forms appear. Unless when 



very unusually vigor- 

 j* ous the pneumococ- 



t cus does not grow 



below 22 C. Its 

 optimum temperature 



y f rf&l i0B is 37 C., its maximum 



42 C. It is prefer- 

 ably an ae' robe, but can 



*. ex i st without oxygen. 



*^ ^ * * It prefers an alkaline 



medium to a neutral, 

 and does not grow 

 on an acid medium. 

 These facts show 

 that when growing 



riG. 52. rraenkel s pneumococcus irom a . 



pure culture on blood agar of twenty-four hours' OUtSlde the body Oil 



growth, some in pairs, some in short chains. artificial media, the 



Stained with weak carbol-fuchsin. x 1000. pneum oCOCCUS is a 



-.comparatively delicate organism. 



The Cultivation of Friedlander's Pneumobacillus. This 

 organism, when present in sputum or in a pneumonic lung, 

 can be readily separated by making ordinary gelatine plate 

 cultures, or a series of successive strokes on agar tubes. 

 The surface colonies always appear as white discs which 

 become raised from the surface so as to appear like little 

 knobs of ivory. From these, pure cultures can be readily 

 obtained. The appearance of a stab culture in gelatine 

 growth is very characteristic. At the site of the puncture, 

 there is on the surface a white growth heaped up, it may j 

 be fully one - eighth of an inch above the level of the 

 gelatine ; along the needle track there is a white granular 

 appearance, so that the whole resembles a white round-headed 

 nail driven into the gelatine (Fig. 53). Hence the name 'nail- 

 like ' which has been applied. Occasionally bubbles of gas 

 develop along the line of growth. There is no liquefaction of 

 the medium. On sloped agar it forms a very white growth 



