IMMUNITY IN PNEUMOCOCCAL INFECTIONS 7 



patient, in such quantity as to neutralise the toxin completely. The 

 organism could then quite easily destroy the toxin-free cocci, and 

 when this was complete the crisis took place. If one supplies to the 

 serum, therefore, the serum of immunised animals containing much 

 antitoxin, the individual will be freed from pneumotoxin much more 

 rapidly ; hence the curative action of the immune serum. 



Mosny was of the opinion, ascribing to the immune serum a 

 " toxinicidal " action, since the diplococcus in this serum preserved its 

 vitality and virulence for a month, while it was destroyed in non- 

 immunised animals in four days. In connection with this, Tizzoni and 

 Panichi (23) have recently showed that it sometimes required several 

 months for the pneumococci to be destroyed by the serum even of highly 

 immunised rabbits. 



Bonome (^4), however, attributes the immunity acquired during an 

 attack of acute pneumonia to the bactericidal property of the blood, 

 and Emmerich voices the same opinion, though he supposed 

 that in the blood of immunised animals there is a substance, arising 

 from the union of the globulin with the toxin shed, or with the 

 toxin in the bacterial cell itself. This substance, which he calls the 

 " Immuntoxinproteidin," has great difificulty in acting on the tissue cells, 

 and is therefore innocuous for those, but it can easily penetrate the 

 bacterial cell, where it is split up into toxin and immunprotein, which, 

 being both in the nascent state, act as virulent poisons for the cocci and 

 rapidly destroy them. 



The French school of workers, headed by Metchnikoff, ascribe the 

 immunisation against pneumococcus entirely to phagocytosis. Issaeff (^S), 

 after a series of most careful experiments, is convinced that there is no 

 bactericidal and no antitoxic power in the serum or tissue-juices, and 

 he ascribes the whole r61e to the leucocyte. Pane is also an active 

 adherent of this theory, and explains the action of his serum on the 

 supposition that, by the introduction of the immune serum, the leucocytes 

 are excited to secrete materials which protect animals against the 

 pneumococci. 



In a series of extensive researches, published by Tchistovitch, of 

 St. Petersburg (26), the exact conditions in the lungs of pneumonic 

 patients and of dogs, in which pneumonia had been artificially induced, 

 were carefully studied. In imitation of Patella's work (1888), he made 



(371) Z I 



