BY R. GREIG-SMITH. 681 



one proceeds in the same manner with the sediments instead of 

 the supernatant suspensions so as to separate out the heavier 

 corpuscles, one finally obtains a suspension which is exceedingly 

 rich in polynuclears and which contains very few of any other 

 kind of white corpuscle. This I call the " polynuclear separate." 

 It is obtained by dropping the blood into 9 c.c. of citrate-saline 

 and rotating the centrifuge quickly until all the cells are deposited. 

 Then they are suspended in 1 % normal saline and slowly rotated 

 in a Metzler hand-centrifuge giving 90 turns in three minutes = 

 2500 revolutions. The supernatant suspension is removed and 

 the deposit is shaken up with 1 % saline and again rotated. The 

 deposit is pipetted into a small tube and quickly rotated to 

 separate the excess of normal saline. After removing the saline, 

 the corpuscles are uniformly mixed by means of the pipette. The 

 white corpuscles travel faster through the fluid, the biconcave 

 erythrocytes being retarded by friction. If spheres and discs are 

 cut out of paraffin and immersed in dilute spirit of such a density 

 that the balls and discs fall slowly, it will be found that the 

 spheres gravitate much faster than the biconcave discs, which 

 fall slowly like parachutes, face downwards and with little 

 inclination to wobble. 



Following is an experiment to determine the distribution of the 

 leucocytes. The plasma was removed by citrate-saline and the 

 corpuscles were distributed in normal saline. The tubes were 

 rotated slowly in the centrifuge as has been already described. 

 The sediments were again shaken up with new saline and rotated. 



I( suspended (45 vols. ) no leucocytes, few dif - 

 suspended < fuse nuclei. 



( sediment (32 vols.) no leucocytes, 



sediment (33 vols.) few leucocytes, chiefly 



'S ^ J mononuclears. 



s M *\ < suspended (21 vols.) many mononuclears. 



£*c£ I / suspended (sediment (16 vols.) few diffuse nuclei. 



0~ WHimpnt ) | suspended (14 vols.) many polymorphs, 



sediment sediment se diment(- 



\ ( "separate") (10 vols.) very many polymorphs 



In the next two experiments, after the removal of the serum, 



the corpuscles were suspended in saline and rotated slowly in a 



wide tube with a drawn-out point for 2,500 revolutions, the 



