262 CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



millimetre : the average is perhaps one or two. In " aseptic " 

 meningitis — i.e., that due to syphilis, or that which occurs in tabes, 

 getteral paralysis, some forms of herpes, and in almost any chronic 

 organic lesion involving the meninges — the number per cubic 

 millimetre is expressed in two or three figures, and usually ranges 

 between 50 and 200. In the acute stage of infantile paralysis it 

 is about the same. In tttberculous meningitis the numbers are 

 higher, and range between 500 and 1,000, but may go much 

 higher, and in " septic " meningitis, including cerebrospinal meningitis, 

 the numbers are very large, often running into tens or even 

 hundreds of thousands. 



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 perchloride 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, syringo- 

 myelia, etc. 



In cerebral tumour the fluid may be under excessive pressure, 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 a hundred or two leucocytes 

 — practically 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 



