CYTO-DIAGNOSIS 3OI 



ordinary clinical methods. Its absence is most important as 

 a negative test; its presence is only equally important if the 

 diagnosis certainly lies between a disease in which this sign 

 is present and one in which it is absent. 



SYPHILIS. In syphilis without involvement of the meninges 

 the cerebro-spinal fluid remains normal, but with the slightest 

 involvement of these structures a lymphocytosis occurs. The 

 Wassermann reaction is present, and this is of the utmost 

 importance as enabling us to distinguish between a syphilitic 

 lymphocytosis and one due to other causes. Where its pres- 

 ence or absence cannot be investigated, the globulin test may 

 be applied. To a small quantity of the cerebro-spinal fluid 

 (that which has been centrifugalized to secure the deposit for 

 microscopical examination may be used) add an equal amount 

 of a saturated solution of ammonium sulphate. A definite and 

 well-marked turbidity, coming on slowly, occurs with syphilitic 

 fluids. Some turbidity occurs with normal fluids, and a few 

 tests should be done on syphilitic and non-syphilitic fluids 

 before the test is used in diagnosis ; but after a very moderate 

 amount of experience the test is one of g'reat value. All three 

 tests the enumeration of the cells, the Wassermann reaction, 

 and the globulin reaction should be used in all cases. 



TUBERCULOUS MENINGITIS has been described already. The 

 lymphocytes may be so numerous as to make the fluid very 

 slightly turbid as compared with pure water, or may number 

 10,000 per cubic millimetre. There is a slight excess of 

 albumen, often no sugar, and sometimes albumose is present. 

 Occasionally the films show a few polynuclear cells, but they 

 are seldom numerous. 



HAEMORRHAGE. With a deep cerebral haemorrhage the fluid 

 is usually clear for two or three days, and then tinged with 

 blood and blood pigment ; the time necessary for this to occur 

 depends on the depth of the haemorrhage from the surface or 

 from the cerebral ventricles. 



When you find blood in the cerebro-spinal fluid, make sure 

 that it does not come from the parietes. If this is the case, it 

 will be most abundant or limited to the commencement of the 

 flow, and if much is present the fluid will coagulate. If it is 

 due to a lesion it will be intimately mixed with the fluid, and 

 will not coagulate. After blood has been present in the cere- 



