SUPPURATION AND SEPTIC DISEASES 139 



Nasgar is prepared as follows: 6 grammes of nutrose and 

 90 c.c. of ascitic fluid are added to 210 c.c. of distilled 

 water. This is heated with constant agitation to boiling, 

 when the nutrose dissolves. This solution is added to 

 600 c.c. of nutrient agar (previously melted) and the mixed 

 liquid is heated in the steam steriliser for half an hour, 

 filtered and tubed and sterilised as for nutrient agar. 

 Cultures are incubated at 37 C. and colonies appear in 

 twenty-four to forty-eight hours. The colonies are 

 characteristic. They are pearl-grey, clear, smooth, and 

 translucent with a firm, regular, oval or round outline. 

 They are larger than the colonies of pneumococci and 

 streptococci which are often found in material from the 

 naso-pharynx. The meningococcus ferments maltose and 

 glucose with the production of acid (distinction from 

 Micrococcus catarrhalis) and fails to ferment saccharose. 

 Muir and Ritchie point out that these fermentation re- 

 actions are most satisfactorily carried out on solid serum 

 media containing one per cent, of the sugar to be 

 tested. 



Mclntosh and Bullock (Lancet, November 27, 1915) use 

 a medium of nutrient 3 per cent, agar, 3 parts; unheated 

 horse- serum, 1 part. The nutrient agar should be neutral 

 to phenolphthalein and made from beef-broth. These 

 authors mention that bile seems to inhibit growth of the 

 meningococcus. 



Agglutination reactions may sometimes be obtained, 

 but negative results are worthless. Morgan (Lancet, 

 1909, ii., 156) found that the serum of patients may 

 agglutinate t}^phoid bacilli in a dilution of 1 in 50 a 

 phenomenon which would be looked upon as a positive 

 reaction to Widal's test. 



A recently suggested diagnostic reaction is performed 

 by adding a drop or two of anti-meningococcus serum to 

 a tube of fresh cerebro-spinal fluid obtained by lumbar 

 puncture and cleared by centrifuging. The tube and a 

 control are incubated at 52 C. for a few hours. If the 

 meningococcus is the cause of the meningitis, a precipitate 

 is said to develop in the tube to which the serum was 

 added, but not in the control. 



Channels of Infection and Pathogenesis (see also p. 265). 

 Cerebro-spinal meningitis is described in the horse, 

 cattle, sheep, and dog, but it is not known if these arise 



