378 APPLICATION OF METHODS OF BACTERIOLOGY 



It stains readily with any of the ordinary aniline dyes, 

 but is decolorized by the method of Gram. It is conspicuous 

 for the irregular way in which it takes up the dye, some 

 cells in a preparation (either from the exudate or from cul- 

 tures) being brightly and intensely colored, others being 

 much less so, or, indeed, often nearly colorless. There is 

 also a marked variation in the size of individual cocci, some 

 being normal, others being apparently swollen. These 

 latter are often pale, with a deeply staining center, giving 

 the appearance of a coccus surrounded by a capsule; it 

 is not improbable that these are degenerated. The ir- 

 regularities here noted are more common in cultures 

 than in fresh exudates from acute cases, and more common 

 in old than in young cultures, a state of affairs fully explained 

 by the self-digestion (autolysis) that this organism is known 

 to experience under conditions of artificial cultivation. 



As seen in cultures, it is commonly arranged in pairs with 

 the individuals flattened at the surfaces of juxtaposition. 

 Sometimes it is seen grouped as four and occasionally as 

 short chains of three or four cells, but never as long chains. 

 Its size is that of the common pyogenic micrococci, and its 

 outline and arrangement in the pus-cells are so like those of 

 the gonococcus that the figure depicting gonorrheal pus 

 answers equally well to illustrate the appearance of the 

 exudate from acute meningitis. 



Though facultative, still its parasitic nature is so 

 dominant that it can only be cultivated with difficulty 

 and uncertainty. The most satisfactory medium for its 

 isolation in pure culture from the diseased meninges is 

 coagulated blood serum (LofEer's mixture), and even here 

 one is not successful with each attempt. So uncertain is 

 its growth under artificial conditions that it is always advis- 



