678 0PS0N1SATI0N FROM A BACTERIAL POINT OF VIEW, ETC., 



saline, etc., was 3 : 5, the ratio of the various constituents being 

 3:3:1:1. 



Ordinary mixture with the addition of 



Cocci per leucocyte. 



normal saline 



distilled water 



21 



24 



sodium hydrate, to make N/80 



phosphoric acid, to make N/80 



8 

 22 



The addition of the distilled water raised the index, probably 

 by lowering the saline content of the test, as will be seen later. 

 The dilute alkali destroyed the majority of the leucocytes; they 

 were either so contracted that the ingested bacteria could not be 

 counted or the nuclei were fused, swollen and destroyed. It is 

 interesting to note that the dilute phosphoric acid had very little 

 effect either upon opsonisation or upon phagocytosis. 



The segregation of the phagocytes in the smears. — In counting 

 the ingested bacteria in the smears, the idea is frequently 

 impressed upon one that the leucocytes are more or less segre- 

 gated. A few polymorphonuclears with a large individual count 

 will be found together and at an adjacent part of the smear 

 several with none, or at most a few bacteria will form a cluster. 

 This is noticeably the case when the suspension is rich in leuco- 

 cytes and counts are made along the margin and within the 

 smear. The cells with a moderate number of bacteria appear to 

 lie on or near the margin, while there is a greater proportion of 

 empty leucocytes within the him. This segregation probably 

 does not affect the count when a sufficient number such as 100' 

 phagocytes are enumerated and the index is not taken to the 

 second place of decimals. When there is a variety of white 

 corpuscles in the corpuscular suspension such as obtains when 

 leucocyte " cream " is employed, and when a clumping of the cells 

 has occurred, as occasionally happens, the clumps generally 

 contain one kind of white blood-corpuscle. The polymorpho- 

 nuclears are in groups by themselves, and the large mononuclears 

 have clumped together. 



But even when 100 cells are counted the index may be false 

 and it is fortunate that sometimes we can tell that it is so and, 



