76 Messrs. Dudgeon and Wilson. On the Presence of [Sept. 11, 



suitable red cells its phagocytic value may be considerably reduced, but 

 that this does not occur in a mixture in whicli haemolysis is absent. It must 

 be apparent from these results that the most accurate information on phago- 

 cytosis must be arrived at when the samples of blood are taken direct from 

 the patient and not mixed with other blood. 



In the experiments about to be referred to, serum and red cells were 

 employed from the same patient, in which, therefore, no htemolysis would 

 occur, and serum and red cells from different sources in which haemolysis could 

 be demonstrated, and lastly serum and unsuitable red cells from different 

 sources in which no haemolytic activity was evident. 



The technique may be briefly described : — The corpuscles were collected 

 in the usual manner in citrated saline and then carefully washed in saline ; 

 the surface layers were removed so as to get rid of as many leucocytes 

 as possible, and a thick suspension of red cells was employed. Equal 

 volumes of the washed undiluted red cells and serum were thoroughly ground 

 ixp in an agate m(jrtar with finely powdered glass. The mixtiire was then 

 placed in glass tubes, sealed and incubated at 37° C. for one hour ; the tubes 

 were centrifugalised at high speed, and a' mixture in three layers was thus 

 obtained, the uppermost consisting of bright red serum, the lowermost of 

 tinged glass, and the intermediate of fragmented red cells. Phagocytic 

 experiments were I then carried out; the first tube contained untreated serum, 

 leucocytes, and micro-organisms, the second tube the " red " serum, leuco- 

 cytes, and micro-organisms. In each case the leucocytes were obtained from 

 the same mixture, and l)elonged to the same specimen of blood as had been 

 employed in the experiments just referred to. The serum before and after 

 treatment was derived from the same source. 



It was found, as a result of these experiments, that when a serum was 

 treated in the manner indicated, whether it was mixed with red cells derived 

 from the same source or different, or whether from tlie red cells which formed 

 a hsemolytic mixture or otherwise, the results were very similar. For 

 example : — 



