2G2 SUSCEPTIBILITY AND IMMUNITY. 



Cation of bacilli, then, apart from the fact that here but one set of cases is 

 embraced, it can be determined that this force is too feeble it can be seen 

 that, during the active growth of the anthrax organism in the blood, the 

 elongating chains of bacilli curve in and out between the corpuscles, but 

 never penetrate the cells. 



From another side the objection has been formulated that in many cases 

 the organism fleets rid of its invaders without the aid of the phagocytes. 

 According to those who support this objection, this happens in the anthrax 

 of pigeons (CzaplewskiJ and of refractory rats (Behring, Franck), in symp- 

 tomatic anthrax of various refractory animals (Rogowicz), and in the septi- 

 ca-mia of vaccinated guinea pigs, due to the Vibrio Metschnikovi (R. Pfeif- 

 fer). A reexamination of the cases here adduced has, however, shown 

 that in each a very considerable phagocytosis can be proved, and that the 

 negative results of the above observers have been due to insufficient methods 

 of observation. 



While accepting that the phagocytes do truly absorb the microorgan- 

 isms, other opponents of the theory have urged that these cells are only 

 capable of including microorganisms already killed by other means, and 

 that living microbes are solely to be found within the cells in those cases 

 where there has been a fatal ending in tuberculosis, mouse septicaemia, and 

 so on. Against this may be brought the fact determined by Lubarsch, that 

 the phagocytes of several animals, refractory to anthrax, take up living ba- 

 cilli that have been injected, with greater eagerness than they include those 

 which have been killed before injection. But, further, this objection may 

 be disposed of by direct observation of bacteria undergoing development 

 from within the interior of phagocytes after the latter hayel>een destroyed 

 by a substance which is at tne same time a favorable medium for bacterial 

 growth as, for instance, beef broth. Such observations have been made 

 upon pigeons rendered immune to anthrax. 



During the last year or two great stress has been laid upon the fact that 

 the body humors themselves possess most marked bactericidal properties, 

 and, in fact, against the theory of phagocytosis has been brought another, 

 baned upon this power of the humors to destroy the microorganisms. Ob- 

 server after observer has remarked that in blood plasma, defibrinated blood, 

 blood serum, and in the blood as a whole, in the removed aqueous humor 

 and other fluids and exudations of the body, many species of bacteria perish 

 after a longer or shorter interval ; and forthwith an endeavor has been 

 made to find in these facts some elucidation of the phenomena of immunity. 

 Yet the more deeply one examines into the question the more one is con- 

 vinced that no relationship exists between the two. Thus it happens often 

 that tho bactericidal property is more developed in susceptible species than 

 in refractory ; so, with regard to the anthrax bacilli, in the very sensitive 

 rabbit the bactericidal properties of the humors are more pronounced than 

 they are m the refractory dog ; and Bearing and Nissen, the two who al- 

 most simultaneously first drew our attention to these phenomena, in their 

 - 



combined research, recently published, admit that, as against the bacteria 

 of anthrax, pneumonia, and diphtheria, this bactericidal property exists to 



iiH-sani.-d.--n-.. m the juices of animals of the same species, whether they 

 be susceptible or -have been rendered immune. Often, again, it has been 

 determined that the blood removed from the organism has a greater power 

 of destroying bacteria than it has within the organism. A small quantity 

 of Wood withdrawn from the body will, in certain instances, kill a mass of 

 I. acilli greater than that which, injected into the circulation, would inevi- 

 tably cause death. Evident ly. therefore, in this bactericidal influence extra- 

 raMUlar phenomena enact an imp,, riant role phenomena, that is which 

 naveno connection with what occurs in the living refractory organism 



'" another point ot view strong ar-nments have been directed against 



this theory of the tissue fluids. It has been shown, especially by the re- 



cnesof M. Hall km.-, that the death of the bacteria transported into or- 



llui.ls is largely due to the sudden change of medium, and that, in 



