LEUCOCYTOSIS AND OPSONIC CONTENT OF SERUM 9 



containing sodium citrate (i % dissolved in '85 % NaCl. 

 solution). The citrated blood was then centrifugalised, the 

 supernatant citrated plasma being removed. The deposit 

 of corpuscles was subsequently washed in a large volume of 

 saline solution, and finally, the corpuscles were brought down 

 as a deposit in the centrifuge, the supernatant saline solution 

 being then removed. 

 3. A uniform emulsion of the microbe to be tested was made in 

 saline solution. The serum, corpuscles and microbe emulsions 

 were then introduced in definite volumes into capillary pipettes, 

 and, after thorough mixing of the contents, the latter were 

 sealed, placed in the incubator for 15' at 37° C, at the end 

 of which time films were made of the mixtures, and after 

 suitable staining (Leishmann, or Ziehl-Neelsen), the number of 

 bacteria ingested by a number of leucocytes was counted. In 

 comparison with the number ingested in the presence of a 

 normal serum this yielded the phagocytic index : 



Number of bacteria ingested by leucocytes in the presence of given serum opsonic 

 Number of bacteria ingested by leucocytes in the presence of normal serum "^ index. 



It is manifestly impossible for one person satisfactorily to carry out 

 experiments of the kind detailed in this paper. We accordingly arranged 

 it so that one of us (L) performed the whole of the blood counts, the 

 other (B) devoting himself to the determinations of the opsonic content. 

 Each worked separately, and at the end of the experiment the results 

 were compared. 



II. — Description of the normal blood-picture in the Rabbit and 

 Guinea-pig and its physiological variations. 



Rabbit. 



The total leucocyte count varies greatly in different rabbits. 

 Goldscheider and Jacob (^9) found a variation of 8000 to 14,000 leucocytes 

 per cub. mm., while Schlesinger {loc. cit.)^ from a series of 100 rabbits, 

 obtained an average count of 10,800, with a variation of 5000 to 17,000. 

 Schulz's (3o) average was 9900. Ricder (3i), Lowit (^s), Ruzicka (33), 



(329) 



