140 



Mr. C. B/uss. An Improved 



[Feb. 21, 



The following points are apparent from these experiments : — ■ 



(1) The leucocytes did vary in the series used for the opsonic estimations. 



(2) No definite relationship was apparent to a high or low count from this 

 leucocyte variation. 



(3) The opsonic count often showed large variations from the mean value, 

 i.e. a large experimental error. 



(4) There appeared to be the all-important constancy of the opsonic figure 

 when the numbers of blanks met during a 50 count was the same or nearly so. 



This last feature suggested that this large content variation might be due 

 to uneven access between leucocytes and bacteria. However, the outstanding 

 fault of the process is this large variation in the leucocyte content, and its 

 occurrence could only be due to differences of (1) appetite or (2) opportunity, 

 or a combination of these factors. 



(1) Appetite. — If the leucocytes have equally as good chances to pick up 

 bacteria in the opsonic mixture, and yet show this variation, it must be 

 presumed physiological, and there is no remedy. 



(2) Opportunity. — It may be that all the leucocytes have similar appetites, 

 but get very different opportunities to pick up bacteria, owing to their 

 uneven distribution in the mixture. 



A scrutiny of the materials used in the old method showed two important 

 defects. 



The Presence of Red Corpuscles. — Although white corpuscles only are 

 concerned in the process, both red and white blood corpuscles are used ; but, 

 since a bacterial suspension not exceeding 500M per cubic centimetre is 

 used, and washed blood corpuscles contain 5000M red and 10M white 

 corpuscles per cubic centimetre, it is evident that for every leucocyte there 

 are 50 bacteria provided, but surrounding this all-important leucocyte are 

 500 obstructing and useless red corpuscles. I therefore decided to abolish 

 the red corpuscles, and this involved the separation of red and white human 

 blood corpuscles. 



The methods which were tried unsuccessfully included — Haemolysis of the 

 red corpuscles ; agglutination by ferric chloride and filtration of the red 

 groups ; filtration of decalcified blood ; sedimentation of decalcified blood 

 after artificially raising the specific gravity. 



However, Dr. Ponders work on leucocytes furnished the nucleus of 

 a successful method. He found that when blood is enclosed in a cell between 

 two glass plates and incubated, there occurs a swarming of polynuclear 

 leucocytes to the glass surfaces, to which they adhere firmly and appear 

 remarkably distorted. 



