280 PHILIP HADLEY 



When the treated serum was tested for its bactericidal properties 

 it was found that they had quite disappeared. Untreated serum 

 still showed a slight growth-inhibiting power. The authors were 

 therefore led to conclude that bactericidal antibodies cannot be 

 considered in the protective action since they can be separated 

 from such serum without causing the degree of protection to be 

 diminished. In a similar manner Weil was able to show later 

 that old immune serum might retain its bactericidal properties 

 after it had lost all protective power. 



The same authors demonstrated by detailed experiments that 

 there is no opsonic action in fowl cholera immune serum. It was 

 clearly shown that there was no phagocytosis of the fowl cholera 

 bacteria in either normal or inununized animals. Sulima 

 (1909) on the contrary, showed that some phagocytosis took place 

 in immune animals but that it was not marked. It is obvious 

 that in dealing with such small organisms as the bacteria of fowl 

 cholera (0.3 to 0.5 n) one must use suitable methods of staining, 

 and much care in examining the leukocytes for evidences of 

 phagocytosis. 



In the work of Huntemiiller (1906) also there is good evidence 

 of the lack of toxin-production by B. avisepticus. One phase of 

 this writer's investigations involved the injection into rabbits of 

 large amounts of bacterial filtrates in order to ascertain whether 

 protective substances could be washed out of the cells. This 

 was not found to be the case; but the point of present interest 

 lies in the fact that the injection of the filtrates produced no ill 

 effect as they certainly would have done if the organisms used 

 had been capable of elaborating so powerful an exotoxin as Dr. 

 Bull's statements imply. 



Taken as a whole, the results of studies on infection and immun- 

 ity in fowl cholera, although appearing to demonstrate that the 

 protective function of fowl cholera immune serum does not rest 

 upon the action of opsonins, nor upon bacteriolytic or bacteri- 

 cidal components (thus, by elimination, suggesting an antitoxic 

 immunity), have failed to reveal the activity of any agent that 

 can properly be regarded as a toxin, either intra- or extra-cellular. 



Within the past few years the present writer (Hadley and 



