DIFFERENTIAL LEUCOCYTE COUNT 23I 



pneumonia, hooping-cough, uraemia, etc. In many cases a small 

 percentage only of the cells is affected, and a good search must 

 be made. 



The fact that it occurs in so many diseases detracts somewhat 

 from its value in diagnosis, but when the question is simply the 

 presence or absence of pus — e.g., in appendicitis— a positive result 

 will usually indicate that suppuration has occurred, and vice versa. 

 Hence it is sometimes of value when the leucocyte count yields 

 uncertain results — i.e., figures between 16,000 to 20,000 per cubic 

 millimetre. 



Myelocytes. — Ehrlich's myelocytes occur in small numbers in 

 many infectious diseases, especially diphtheria, and occasionally 

 in forms of anaemia, but they are only present in large numbers 

 in myeloid leucocythaemia. Cornil's myelocytes are practically 

 limited to the latter condition, where the two forms frequently 

 together make up 60 per cent, of all leucocytes. 



Eosinophiles. — An increase of eosinophiles (eosinophilia) occurs 

 to a small extent in numerous diseases, and is of diagnostic 

 importance in the following : 



I. In diseases due to animal parasites. Here the increase may 

 be very great, as in trichinosis, where the eosinophiles usually 

 form 40 to 80 per cent, of all leucocytes, a fact of great impor- 

 tance, and absolutely distinguishing the disease from typhoid 

 fever, rheumatism, and other diseases which may be confounded 

 with it ; rarely, however, there may be no eosinophilia, so that 

 its absence does not definitely exclude the disease. In bilharzia 

 disease there is often, though not always, a mild eosinophilia. 

 There is practically always an increase in ankylostomiasis. It 

 may be moderate, or may reach 70 per cent. This fact enables 

 infected individuals to be picked out of a gang of workmen with 

 much less trouble than by an examination of the feeces. In 

 diseases due to other intestinal worms (ascarides, oxyuris, taeniae), 

 there may or may not be eosinophilia. 



In hydatid disease there is frequently a moderate eosinophilia, 

 and sometimes a great one. This is important in the diagnosis 

 between hydatid and abscess of the liver, since in the latter 

 condition the eosinophiles are usually scanty. In such a case 

 the higher the count is above 4 per cent., the more likely is the 

 disease to be hydatid, and vice versa. 



In the only case of cysticercus I have seen the eosinophiles 

 ranged between 5 and 7 per cent. 



