304 BACTERIOLOGY. 



nary 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 cultures) 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 centre, giving the appearance of 

 a coccus surrounded by a capsule. It is not improbable 

 that these are degenerated or involuted cells. The 

 irregularities here noted are more common in cultures 

 than in fresh exudates from acute cases, and more 

 common in old than in young cultures. 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 micro- 

 cocci, and its outline and arrangement in the pus-cells 

 are so like those of the gonococcus that the figure depict- 

 ing gonorrhoaal pus answers equally well to illustrate the 

 appearance of the exudate from acute meningitis. 



While a facultative saprophyte, still its parasitic 

 nature is so marked that it can only be cultivated with 

 some trouble and uncertainty. The most satisfactory 

 medium for its isolation in pure culture from the dis- 

 eased meninges is coagulated blood-serum (Loffler's 

 mixture), and even here one is not successful with each 

 attempt. So uncertain is its growth under artificial 

 conditions that it is always advisable to inoculate a 

 number of tubes with relatively large quantities of the 

 exudate, and even then growth often occurs in only a 



