INFECTION AND IMMUNITY. 425 



tion has rendered questionable the advisibility of its 

 unconditional adoption. 



The first severe blow that this theory received was 

 given by Nuttall, 1 in his work upon the anti -bacterial 

 action of the animal economy. In these experiments 

 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, pos- 

 sessed 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, 2 as far back as 1874, demon- 

 strated that considerable quantities of septic material 

 could be injected into the circulating blood without ap- 

 parently 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 appreciable 

 numbers of living bacteria could be injected 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 decomposing fluid, the blood 

 drawn from the animal after from twenty-four to forty- 

 eight hours showed no especial tendency to decompose, 



1 Zeitschrift fur Hygiene, 1888, vol. iv. 



2 Jahresbericht der Schlesischen Ges. fur Cultur, 1874 ; Jahr. lii. p. 179. 



