INFECTION AND IMMUNITY. 405 



Nuttall showed positively that the part played by the 

 leucocytes was not essential to the destruction of viru- 

 lent bacteria in the blood of animals, but that the serum 

 of the blood, when quite free from cellular elements, 

 possessed this power to a degree equal to that of the. 

 blood when all the constituent parts were present. In 

 the blood, as such, phagocytosis could be seen, but, as a 

 rule, the bacteria presented evidence of having under- 

 gone degenerative changes before they had been taken 

 up by the wandering cells. 



Contrary to the notions in existence at the time, 

 Traube and Gscheidlen,' as far back as 1874, demon- 

 strated that considerable quantities of septic material 

 could be injected into the circulating blood without 

 apparently any effect upon the animal. As a result 

 of these experiments, the question that naturally 

 presented itself was : Does the animal organism 

 possess the power of rendering septic organisms inert, 

 and if so, to what extent? Their further work showed 

 that appeciable numbers of living bacteria could be in- 

 jected into the circulation of warm-blooded animals 

 without producing any noticeable effect. Particularly 

 was this the case with dogs. If they injected into the 

 circulation of a dog as much as 1.5 c.cm. of decompos- 

 ing fluid, the blood drawn from the animal after from 

 twenty-four to forty-eight hours showed no especial 

 tendency to decompose, though it was kept under obser- 

 vation for a long time. They believed this power, of 

 rendering living organisms inert, to be possessed by the 

 circulating blood to only a limited degree, for, after the 

 injection of much larger amounts of the putrid fluid 

 into the blood of the animal, death usually ensued in 



1 Jahresbericht der Sohlesischen Ges. fur Cultur, 1874 ; Jahr. 111. p. 179. 



18* 



