DIFFERENTIAL LEUCOCYTE COUNT 265 



P for polynuclear, E for eosinophile, etc., and to put these 

 down in blocks of five each way, thus : 



PPPLE 

 PPLLH 

 LPPPP 

 PLLPL 

 PPPLP 



In this way you can tell at any time how many leucocytes 

 you have counted. It is much quicker to dictate the numbers 

 to a second person, who takes them down as described; you 

 do not then have to look constantly from the microscope to 

 the paper and vice versa, and the whole process takes a very * 

 few minutes unless the leucocytes are very scanty. 



For most clinical purposes 400 leucocytes will be enough to 

 count, though where very great accuracy is required 1,000 is 

 not too many. Having counted the required number, pro- 

 ceed to count the numbers of P's, L's, etc., and reduce them 

 to a percentage. 



Whilst making the differential count keep a sharp look-out 

 for abnormal leucocytes, abnormal red corpuscles (see p. 269), 

 parasites, etc. The collections of blood platelets which form 

 such a prominent feature in some blood films should not be 

 confounded with anything else, as they are quite character- 

 istic, though a single blood platelet lying on the top of a red 

 corpuscle may look very like a young malaria parasite. Each 

 platelet is a very small mass which stains blue or purple with 

 Jenner's stain, and often appears hollow or irregular in shape, 

 and they are often grouped in masses of quite large size. 



ALTERATIONS IN DISEASE. 



Lymphocytes. They may be relatively increased (e.g., to 

 figures above 30 per cent.) when the total figures are normal 

 or raised. These findings have different meanings. 



Lymphocytosis with normal or lowered total counts occurs 

 in pernicious anaemia, typhoid fever, uncomplicated tuber- 

 culosis (but not always), in some cases of purpura (so-called 

 idiopathic purpura), in splenic anaemia, and occasionally in 

 syphilis, Hodgkin's disease, and some other diseases. 



Lymphocytosis with a high total count occurs as a normal 

 condition in infancy, and is accentuated both as regards the 



