CHAPTER XI 



PHAGOCYTOSIS 



EARLY investigations into the fate of bacteria within the infected 

 animal body were largely carried out by pathological anatomists, and 

 the observation of the presence of micro-organisms within the cells 

 of the animal and human tissues was definitely made as early as 

 1870. Hayem, 1 Klebs, 2 Waldeyer, 3 and others, saw leukocytes con- 

 taining bacteria but failed to interpret this in the sense of possible 

 protection. The process was regarded rather as a means of trans- 

 portation of the bacteria through the infected body, or it was as- 

 sumed that possibly the micro-organisms had entered these cells be- 

 cause of the favorable nutritive environment thus furnished. 



The first to suggest that such cell ingestion might represent a 

 method of defence was Panum, 4 who referred to it as a vague possi- 

 bility. A similar but more convinced expression of this opinion 

 was made in 1881, according to Metchnikoff, 5 by Roser in explaining 

 the resistance of certain lower animals and plants against bacteria. 

 But Roser brought no experimental support for his contention, and 

 little attention was paid to his assertion. 



The significance of cell ingestion as a mode of protection against 

 bacterial invasion, therefore, was hardly more than a vague sugges- 

 tion when Metchnikoff, who, though a zoologist, had become intensely 

 interested in the problem of inflammation, began to experiment upon 

 the cell reaction which followed the introduction of foreign material, 

 living or dead, into the larvae of certain starfishes (Bipinnaria). 



Pathologists, at this time, held complicated views of inflamma- 

 tion which involved complex coordinated reactions of vascular and 

 nervous systems, and Metchnikoff 's primary purpose was to observe 

 reactions to irritation in simple forms devoid of specialized vascular 

 or nervous apparatus. He noted in these transparent, simple forms 

 of life that the foreign particles were rapidly surrounded by masses 

 of ameboid cells and reached a conclusion which, in his own words, 

 is expressed as follows : 



1 Hayem. C. E. tie la Soc. Biol, 1870. 



2 Klebs. Pathol. Anat. der Schusswinden, 1872. 



3 Waldeyer. Arch. /. Gynekol, Vol. 3, 1872. 

 * Panum. Virch. Arch., Vol. 60, 1874. 



5 Metchnikoff. "L'lmmunite dans les Maladies Infectieuses." 



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