THE MEMXGOCOCCUS GROUP 3o9 
havintj shown that the organisms are present in the blood stream very 
early in the disease. 
About 25 cc. of the serum are administered at each injection. The 
injections are repeated every few hours, if necessary. The mortality 
varies with the time of administration of the serum. It is about 25 
per cent on the a\erage when the serum is given before the seventh day, 
and about 43 per cent if it is injected later than the seventh day of the 
disease. 
Bacteriological Diagnosis. — (a) M or pJwlof/ica I.— The demonstration of 
(iram-negative, biscuit-shaped diplococci in purulent spinal fluid from 
patients exhibiting the characteristic clinical symptoms is sufficient 
to estal)lish a diagnosis of the meningococcus. It is to be remembered 
that the spinal fluid is clear for the first twenty-four hours of the dis- 
ease, and usually clear after the tenth day to the fourteenth day, even 
in untreated cases. Centrifugalization in sterile tubes must be resorted 
to in such cases; the sediment is examined as above. Smears from the 
nasopharynx, from middle-ear infections, and from suspected carriers 
cannot be definitely diagnosed upon morphological characters alone. 
Cultural aufl serological characteristics must be studied as well. 
Cultural Characters. — Blood cultures should be made. Spinal fluid 
removed aseptically (and centrifugalized if the fluid is clear) and 
material from the nasopharynx, nasal cavity, or accessory nasal sinuses^ 
is spread upon blood or ascitic fluid agar, or if these are not available, 
upon Loffler's blood serum, and incubated at 37° C. Material for 
culture from the nasopharynx is obtained upon sterile swabs, which 
must be rubbed briskly upon the posterior wall below the level of the 
nose and above the level of the mouth. Care must be taken to avoid 
touching the nasal or buccal mucous membrane. After twenty-four to 
forty-eight hours' incubation, small, clear, round colonies develop in the 
majority of cases in which meningococci are present. These should be 
transferred to ascitic broth (preferably containing 1 per cent of glucose 
and a small piece of calcium carbonate) and examined after twenty- 
four hours' incubation at body temperature. If growth occurs, 
inoculation should be made in ascitic fluid, glucose and ascitic fluid 
maltose broths to determine if acid is produced. The serological type 
is determined from the original ascitic broth culture, using specific 
type sera of high titer. An agglutination," positive at one-half or (me- 
third of the agglutination limit of the specific serum, provided the 
controls are adequate, fixes the type and establishes the diagnosis. 
Several diplococci have been found which resemble the meningo- 
coccus microscopically but which dift'er from it in their fermentation 
reactions. A negative result does not exclude the possibility of an 
infection with the meningococcus; negative cultivations occur quite 
• Material for examination from the nasopharynx is best obtained upon sterile swabs; 
the infected swab should be immediately rubbed over the surface of a series of blood 
or ascitic agar tubes or ascitic agar plates. This method is particularly adapted to 
the examination of suspected carriers. 
