33$ R6LE OF THE BACTERIOLYSINS IN RECOVERY 



appears to diminish the more it is investigated. In general terms, 

 there is no doubt as to the fact that the presence of abundant 

 bacteriolytic substances must be regarded as a cause of immunity : 

 thus, animals may be rendered passively immune, e.g., to intra- 

 peritoneal injections of typhoid or cholera by antecedent or 

 simultaneous injections of powerful bactericidal serum. But 

 further investigation shows that even in this phenomenon there 

 are certain features which must lead us to regard the process of 

 bacteriolysis as of subordinate importance, or even as harmful. 

 In the first place, the demonstration of the fact that the opsonic 

 action of a powerful antityphoid serum (as determined by the 

 process of dilution until extinction of the property occurs) is pro- 

 portionate to its bactericidal action, and other facts already noticed, 

 have led us to the belief that immune body or amboceptor can 

 play the part of an opsonin, and, further, that it does so when 

 present in amount so small that its bacteriolytic action is but slight 

 or not apparent. It is, therefore, in the highest degree probable 

 that the passive immunity conferred by the injection of a bacterio- 

 lytic serum is due to the opsonizing action of this serum, manifested 

 even when diluted with the juices of the animal into which it is 

 injected. 



In the second place, there is this main difference between the 

 destruction of bacteria within the leucocyte after phagocytosis 

 has occurred and the extracellular solution by immune body and 

 alexin : in the former case it is unusual for the endotoxins to be 

 set at liberty, so that as soon as a bacterium has been taken up by 

 a leucocyte, we believe that, as a rule, its capacity for harm has 

 been removed. It undergoes solution within the protoplasm of the 

 leucocyte, which, as appears from the studies of the French school, 

 is peculiarly insusceptible to the action of toxins, is destroyed by 

 the digestive juices, or by other means, and is not, at least in the 

 majority of cases, set free to injure the tissue cells. It is other- 

 wise with the solution of bacteria which takes place from the 

 action of bacteriolytic antibodies, for here the endotoxins are set 

 free, so that the presence of these antibodies, though undoubtedly 

 developed as a part of the defensive mechanism, may be a source 

 of added danger to the animal. For example, if an intraperitoneal 

 injection of a large dose of cholera vibrios be made into the peri- 

 toneal cavities of two animals, and in one some anticholera serum 

 be added, it is often found that this animal dies very rapidly with 

 symptoms of acute intoxication, whilst the other survives longer 



