l6 QUATERCENTENARY STUDIES IN PATHOLOGY 



The serum, mixed in equal parts with a i - i,cxx),ooo dilution of the 

 living culture failed to destroy the growth. The number of bacilli in the 

 I - 1,000,000 dilution, as estimated by Wright's method, showed — 



10 mm3 of I : 1,000,000 culture dilution, i colony. 



10 mm3 of I : 1,000,000 m o i? 



10 mm3 of I : 100,000 n 13 n "i Average 



10 mm3 of 1:100,000 »i 17 It / 15. 



Thus the serum had exerted no bactericidal effect in vitro, inasmuch as 

 not one single pyocyanic bacillus had been destroyed. As the serum was 

 examined direct from the body of the rabbit, it would appear to be 

 unlikely that in vivo the bacilli are destroyed by bactericidal action, as 

 has been maintained by Wassermann. 



The results of all the immunisation experiments have failed to show 

 anything like the degree of immunity obtained by Wassermann. 



As was mentioned above, Gheorghiewsky came to the conclusion that 

 pyocyanic immunity owed its power to the destruction of the bacilli by 

 the phagocytes. Wright and Douglas have, however, shown that the 

 blood fluids play a cardinal role in the production of phagocytosis, and 

 on testing the sera of rabbits immunised against the bacillus pyocyaneus 

 it was actually found that the opsonic power of the serum may be con- 

 siderably greater than that of normal animals. Such immune serum as 

 we have seen possesses no bactericidal power in sensu strictori. 



A few experiments were also made with pyocyanine isolated from 

 cultures. The cultures, rich in this pigment, were shaken up with 

 chloroform, the pyocyanine passing into solution. By allowing the 

 chloroform to evaporate, the well-known blue crystals were obtained. 

 As was found by Ledderhose, Charrin and Legros, pyocyanine prepared 

 in this way presented no toxic properties. I have not been able to 

 confirm the statement of Charrin and Gheorghiewsky that immune 

 serum inhibits pyocyanine formation. 



Conclusions. 



1. Guinea-pigs are highly sensitive to the action of bacillus 

 pyocyaneus. 



2. The filtrates obtained from living cultures of virulent pyocyanic 

 bacilli are not toxic to guinea-pigs and rabbits except in enormous doses. 



(172) 



