300 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



Having counted the leucocytes, proceed to centrifugalize 

 the fluid, and examine films from the deposit by the wet or 

 dry method. The former shows the cells more clearly, and 

 is to be preferred when a cytological examination only is 

 required, as in the diagnosis of tabes or general paralysis. 

 Where bacteria are to be looked for, dried films should be 

 made and stained by Jenner's method, or fixed with per- 

 chloride and stained by thionin. Then proceed with the 

 chemical examination of the fluid already described. 



Normal fluid occurs in any nervous disease not attended by 

 an organic lesion of the meninges : deep cerebral tumours, 

 hysteria, deep cerebral haemorrhages, peripheral neuritis, 

 epilepsy, syringomyelia, etc. 



In cerebral tumour the fluid may be under excessive pres- 

 sure, so that it squirts out of the needle; in such cases there 

 may be great relief to the headache after the withdrawal of a 

 considerable amount of fluid. With a cortical tumour there 

 is usually slight lymphocytosis. According to some writers, 

 the pressure is moderately raised in epilepsy. 



Aseptic meningitis, using the term to indicate that there 

 are no cultivable organisms present, occurs in syphilis, tabes, 

 general paralysis, superficial gummata and other tumours, 

 insular sclerosis, if any of the patches are superficial, chronic 

 alcoholic meningitis, hypertrophic pachymeningitis, acute 

 softening, some cases of herpes, etc. In these cases we may 

 expect to find twenty-five to two hundred leucocytes prac- 

 tically all of which are lymphocytes per cubic millimetre. In 

 addition there is usually a slight excess of albumen, and sugar 

 is present, though sometimes reduced in amount. 



A slight lymphocytosis, therefore, does not in itself give a 

 clue to the diagnosis unless it rests between two conditions, 

 one of which causes lymphocytosis, whilst the other does not. 

 Thus, if the diagnosis is either insular sclerosis or hysteria, 

 the presence of a moderate leucocytosis tells strongly in 

 favour of the former. Similarly in the differential diagnosis 

 between tabes and peripheral neuritis, and between general 

 paralysis and most of the diseases which it simulates. It is to 

 be noted that excess of lymphocytes in the cerebro-spinal fluid 

 is a very early and a very constant finding in these affections, 

 and often occurs long before the diagnosis can be made by 



