214 THE ACUTE PNEUMONIAS 



regular, though on some media slight crenation may appear. The 

 colonies may be of considerable size, reaching sometimes a 

 diameter of 2 to 3 mm. on the third day. On plain agar the 

 colonies are very much smaller, and sometimes no growth 

 occurs ; sub-cultures especially often fail to give any growth 

 on this medium. In serum bouillon the organism produces a 

 general turbidity with formation of some deposit after a day or 

 two. It ferments maltose, galactose, and dextrose with acid 

 production, a property which distinguishes it from the micro- 

 coccus catarrhalis (vide infra}. Buchanan has pointed out that 

 this may be demonstrated by making up lots of Loifler's medium 



(p. 40) in Petri dishes 



. with each of these sugars 



* * added. In all cases 



/ * *** ., * 5 . growth occurs best when 



*' *.%*** /V the medium has a neutral 



v *"* ? V * % ^\ or very slightly alkaline 



+ ^* -*, , **; **** '-/ % *t** reaction. In cultures the 

 , .** *% "* '*.!V*.' * *' organism presents the 

 . *%**** V * same appearance as in the 



** - ** . . , - . **, body and often shows 



' *%*, * % * tetrad formation. There 



. "' * ** ***** T' is also a great tendency 

 i t^, ^ t to the production of in- 



*-.+ .' f . * volution forms (Fig. 73), 



, % X, \+* many of the cocci be- 



* coming much swollen, 



FIG. 73,-Pure culture of diplococcus intra- stainin g badl y. and after ' 

 cellularis, showing involution forms. wards undergoing disin- 



tegration. This change, 



according to Flexner's observations, would appear to be due to 

 the production of an autolytic enzyne, and he has also found that 

 this substance has the property of producing dissolution of the 

 bodies of other bacteria. The life of the organism in cultures is 

 a comparatively short one ; after a few days cultures will often 

 be found to be dead, but, by making sub-cultures every three or 

 four days strains can be maintained alive for considerable periods. 

 The organism is readily killed by heat at 60 C., and it is also 

 very sensitive to weak antiseptics ; drying for a period of a day 

 has been found to be fatal to it. The facts established accord- 

 ingly show it to be a somewhat delicate parasite. 



As stated above, the organism occurs in the exudate in the 

 meninges and in the cerebro-spinal fluid, and it can usually be 

 obtained by lumbar puncture. In acute cases, especially in the 



