222 Transactions of the Society. 



nized, Further, it appears that people may be carriers of the 

 germs, and, therefore, centres of infection, possibly for weeks, and 

 never .manifest any specific symptoms, indeed appearing to be in 

 full health. It complicates matters somewhat that the germ 

 producing the disease is, in its microscopic appearance and 

 straining reactions, very similar to some two or three other 

 organisms that are met with in healthy, or inflamed, throats. 

 Weichselbaum, who discovered and first described the meningo- 

 coccus, as it is called, isolated it from the serus and seropurulent 

 fluid drawn, by tapping, from the cerebro-spinal canal of a patient 

 suffering from what was spoken of as "spotted" fever or cerebro- 

 spinal meningitis or cerebro-spinal fever. He found the organism, 

 to which he gave the name, Biplococcus intracellularis meningitidis, 

 not only lodged in the pus cells separating out in the sediment of 

 the fluid when allowed to stand or centrifugalized, but also lying 

 free between the cells. The meningococcus, " for short," is readily 

 stained by the basic aniline dyes, and is Gram-negative, in this, 

 however, as noted above, resembling at least two other diplococci. 

 It grows best at the temperature of the body, and, except under 

 very favourable, conditions and in specially good nutrient media, 

 its growth is checked completely when the organism is exposed to 

 a temperature below 23° C. As taken from the spinal canal the 

 organism seems to be strongly parasitic, and does not grow at all 

 readily on ordinary nutrient media, and only sparsely on special 

 media. It may be, of course, that many of those seen under the 

 Microscope are dead, and as a matter of fact many of them stain 

 very imperfectly (this lending support to the view that their life 

 is a brief one, and that they do not multiply, except under very 

 favourable conditions), for even when the number of diplococci 

 seen under the Microscope is large, the number of colonies growing, 

 on the most suitable medium, is comparatively small. The most 

 suitable medium for its growth is said to be agar containing a 

 small amount of nutrose and human serum or ascitic fluid, but all 

 my experience has been with nutrient agar, to each tube of which 

 a few drops of human or rabbit blood are added just before it 

 consolidates. This is certainly an excellent medium, the haemo- 

 globin supplying something exceedingly favourable (perhaps too 

 favourable for our purpose) to the growth of the organism. With 

 the permission of my colleague, Captain Gaskell, I show a drawing 

 made from preparations in which the meningococcus is seen lying- 

 in and around the pus cells. Here the shape of the organism and the 

 marked lack of staining power of some of the diplococci is evident. 

 The organism, which measures 1 /x or slightly more in diameter, 

 usually occurs in pairs of flattened slightly kidney-shaped bodies 

 with their concave surfaces facing each other, and with a small 

 clear band or space between. Sometimes a single coccus may be 

 seen, whilst again tetrads or groups of four may be met with. It 



