680 OPSONISATION FROM A BACTERIAL POINT OF VIEW, ETC., 



It is clear from these indices that a segregation has occurred 

 and that the polymorphonuclears within the tip of the smear 

 contain fewer bacteria than those of the margin. 



While writing this paper some time after the work had been 

 done, I saw that the matter had received attention, especially 

 from the workers in the Johns Hopkins Hospital."* 



Jeans and Sellards showed that variations in the counts 

 occurred in different parts of the same smear. Moss found that 

 the leucocytes with the fewest bacteria were at the base of the 

 smear and those with most at the tip. He believed that in the 

 process of smearing the smaller leucocytes were the first to slip 

 under the spreader and were accordingly deposited towards the 

 base of the smear. The larger leucocytes were carried to the end 

 of the smear, where they were deposited. 



The polynuclear "Separate." — It is the usual practice and one 

 that was suggested by Wright, to skim off the top layers of the 

 centrifugalised blood-corpuscles, or better to gently rotate the 

 tube, when the upper layers are loosened and mix with the small 

 quantity of saline which is allowed to remain above the deposit. 

 The thin suspension is removed and centrifugalised in a small 

 hematocrit tube. The whole of the deposit of the top portion 

 only is taken. This so-called " cream " is rich in white blood- 

 corpuscles. It occurred to me that a better separation might be 

 obtained by slowly centrifugalising the suspension, until half of 

 the cells had deposited, removing the supernatant suspension, 

 shaking it up and again slowly centrifugalising until half had 

 deposited and once more repeating the process, a suspension might 

 be obtained which would contain all the leucocytes of the original 

 suspension. Although the leucocytes are said to have a lower 

 specific gravity than the erythrocytes and although one would 

 expect to obtain all the leucocytes by this centrifugalising, it is 

 strange that there is an utter absence of polynuclears in the 

 " cream " centrifugalised in this manner. One may obtain lym- 

 phocytes and a few mononuclears, for these constitute the white 

 film that is found on the top of the centrifugalised sediments. If 



* Johns Hopkins Hospital Bulletin, xviii. Nos. 195, 196. 



