872 PHAGOCYTES AND PHAGOCYTOSIS IN IMMUNITY 



with staphylococci and tubercle bacilU ; of Rosenow' with pneumococci, streptococci, 

 tubercle bacilli, and staphylococci; and of Hektoen^ with hemopsonins — that normal 

 opsonins, like the immune opsonins, are more or less specific. 



The origin of normal opsonins is not known. Wright found them present in the 

 normal blood of man for Staphylococcus pyogenes, pneumococci. Brucella melitensis 

 B. pestis, B. anthracis, B. coll, B. typhosus, Vibrio cholerae, B. tuberculosis, but absent 

 for B. diphtheriae and B. xerosis. Tunnicliff'' found that the anti-infectious power of 

 the blood of infants, so far as staphylococci, streptococci, and pneumococci were con- 

 cerned, was at a low level at birth, fell even lower during the first few months of life, 

 and rose to the adult level at about the third year. She also determined that exudate 

 leukocytes are more active phagocytically than leukocytes from the blood of the same 

 animals; as are also those in the blood of cases of acute infection, e.g., pneumonia, 

 scarlet fever. 



Attention was called by Wright and Reid^ to the fact that in artificial experiments 

 some leukocytes engage in phagocytosis in the absence of opsonin. They called this 

 "spontaneous phagocytosis." They found that the amount of this spontaneous phag- 

 ocytosis could be increased by diminishing the amount of sodium chloride in the 

 serum or suppressed by increasing the amount. 



This points to the necessity of considering the physical consistency of the leu- 

 kocytes themselves as a factor in phagocytosis. Tunnicliff showed that leukocytes 

 from inflammatory exudates showed greater phagocytic power than those from the 

 normal circulating blood, and Kite and Wherry^ found individual differences in their 

 glass adhesiveness. It is probable that leukocytes are more active when they are hy- 

 drated. 



When bacteria fail to absorb opsonin they show great resistance to phagocytosis as 

 shown by Rosenow,*^ who was able to extract from virulent pneumococci with phys- 

 iological salt solution a substance he called "virulin" which inhibited the action of 

 pneumococcus opsonin, 



THE PHAGOCYTES AND THEIR ORIGIN 



The white cells of the blood may vary considerably in number even in apparently 

 healthy individuals. The normal average lies between 7,300 and 7,500 cells per cubic 

 millimeter. After the introduction of the technique of cell-staining and differentiation 

 and following the work of Ehrlich came the recognition of six types of cells : the neutro- 

 philic, eosinophilic, and basophilic leukocytes; the small lymphocytes with which were 

 included certain intermediate forms; large lymphocytes or mononuclear forms; and 

 the transitional cells. 



There are five types of granulations, only three of which occur in the human 



' Rosenow, E. C: J. Infect. Dis., 4, 285. 1907. 

 ^Hektoen, L.: ibid., 5, 249. 1908. 



3 Tunnicliff, R.: ibid., 7, 698. 1910; Tr. Chicago Path. Soc, 8, 208. 191 1; /. Infect. Dis., 8, 302. 

 1911. 



4 Wright, A. E., and Reid, S. T.: loc. cil. 



sKite, G. L., and Wherry, W. B.: /. Infect. Dis., 16, 109. 1915. 

 'Rosenow, E. C: ibid., 4, 285. 1907. 



