LEUCOCYTOSIS AND OPSONIC CONTENT OF SERUM 7 



that various authors have recorded by the employment of substances 

 producing leucocytosis. 



The first experiments in this direction were made by Loewy and 

 Richter (^9), who succeeded in protecting rabbits against experimental 

 pneumococcic infections, by injecting substances like spermin, pilocarpin 

 and albumoses. These experiments were further extended by Jacob 

 (20), who also noted that animals inoculated in the leucopenic period, 

 following the injection of albumoses, always succumbed, while those 

 infected during the period of hyperleucocytosis were markedly protected. 



Hahn (21) employed yeast-nuclein in dogs and tuberculin in man, and 

 showed that the blood drawn during the stage of hyperleucocytosis had 

 a higher bactericidal power than normal blood. The period of immunity 

 was, however, always very short, and in striking contrast to that obtained 

 by previous inoculation of extracts or sterilised cultures of the organism 

 employed for infection. 



Very complete and convincing experiments were made by Pfeififer 

 and Issaefif (22) in experimental cholera infection. They showed that the 

 inoculation of guinea-pigs with nuclein, serum of cholera convalescents, 

 serum of healthy persons, bouillon, urine, and salt solution, gave a 

 protecting power which diminished in the order of the substances named. 



Other subtances as tissue-fibrinogen (Wooldridge (^3) )j testicle 

 emulsion (Zacharofif (^4) ), thymus and lymph-gland extracts (Brieger, 

 Kitasato and Wassermann (^5) )j gluten-casein, legumin (Buchner, loc. 

 cit), were found, on injection, to give varying degrees of protecting power, 

 attributable to the hyperleucocytosis produced by them. 



With these and many other substances, different observers have, 

 however, frequently obtained different results, a fact which is not 

 surprising when one considers the well known differences in the 

 individual response to such substances, the mode of administration, and 

 the amount inoculated. 



In all these instances of increased natural resistance associated with 

 hyperleucocytosis, it would be exceedingly interesting to ascertain with 

 exactitude how the two bodies amboceptor and complement — concerned 

 in the destruction of micro-organisms — were respectively influenced by 

 the leucocytic variation. Very few results, however, are forthcoming in 

 this direction, but it appears from the work of Nolf (^6), Muller (^7)^ 

 Wassermann (Joe. cit.) and Longcope (^s) that it is the complement and 



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