CYTO-DIAGNOSIS 261 



unmixed with other cells. But chronic inflammation of the 

 peritoneum, with or without mild sepsis, is frequently present, 

 and polynuclears and lymphocytes frequently occur. 



Malignant Disease.— Here the large vacuolated endothelial 

 cells shown on Plate X., Fig. 3, may occur, and are extremely 

 suggestive, though they cannot be taken as definite proof. Rarely 

 you may find definite malignant masses, which, of course, settles 

 the diagnosis. In other cases there may be numerous polynuclear 

 cells, and in yet others mostly lymphocytes. The presence of an 

 abundance of red cells is suggestive, provided you can be sure it 

 does not come from the puncture, in which case it will be most 

 abundant at the beginning of the flow. It will be apparent that 

 the diagnosis of malignancy cannot be made in the majority of 

 cases by the cytology of the ascitic fluid. 



The Meninges. 



Here the technique is somewhat different. Clotting is not so 

 likely to occur, and when it does so is much slower, so that if the 

 fluid can be examined in any reasonable time there is no necessity 

 to break up the clot. This is fortunate, since the number of 

 cells present is of importance, and they cannot bei counted in a 

 specimen which has coagulated. My own method is to count the 

 cells directly, without concentration and without dilution, in a 

 Thoma-Zeiss counting-chamber, by the method used for the 

 leucocytes and described on p. 212. If the specimen has had time 

 to sediment, shake it thoroughly ; then place a loopful or two on 

 the counting-chamber, cover it, getting Newton's rings, and allow 

 to settle. Then arrange the microscope so that the diameter of 

 the field is equal to that of eight small squares, and proceed to 

 count the leucocytes on forty or eighty fields ; in the former case 

 the result multiplied by two gives the number of cells per cubic 

 millimetre, whilst if eighty are counted the number is given 

 direct, no calculation being necessary. (There is no dilution of 

 the fluid, and you have counted the actual number in |- or i cubic 

 millimetre.) The only difficulty arises if red corpuscles are 

 present ; they may be distinguished by being less granular and 

 less refractile than the leucocytes, and are not to be counted. 



The following rules may be taken as approximately correct for 

 the numbers of cells met with in various conditions. In health 

 there may be none, and never more than single figures per cubic 



