270 BACTERIOLOGY 



most important defensive mechanism possessed by the body, 

 and believed both natural and acquired immunity to be 

 referable to it; in the former case regarding it as a natural 

 endowment, in the latter as a function that had been excited 

 by the specific stimulus offered by the organisms or their 

 poisons that were concerned in the primary attack of disease 

 from which the animal recovered, or by the organisms used 

 in purposely exciting a modified form of the disease by one 

 or another of the modes of protective vaccination. 



As the phenomenon of phagocytosis could easily be ob- 

 served under the microscope, and its observation therefore 

 accessible to all interested in the question, the plausibility 

 of the doctrine at once attracted many adherents, and 

 Metchnikoff's views were everywhere accepted as the prob- 

 able explanation of the defensive mechanism of the body 

 against infection. 



In a little while, however, Fluegge, of Breslau, perceiving 

 the incompetency of both Chauveau's and Pasteur's doc- 

 trines, observing occasional inconsistencies in Metchnikoff's 

 teaching, and recalling certain significant reactions of the 

 blood that had appeared in the course of experiments by 

 Traube and Gscheidlen, by Fodor, by Rauschenbach, and 

 by Grohmann, determined to subject the whole question 

 to. an experimental critical review. 



To Nuttall, an American working in his laboratory, was 

 assigned the question of determining if the cell-free blood, 

 or the plasma, was, as had been suggested by Grohmann, 

 possessed of germ-destroying properties. Nuttall's work 

 resulted in a blow to Metchnikoff's doctrine that for a long 

 time seemed to be fatal. He demonstrated that certain 

 virulent bacteria were rendered incapable of development, 

 incapable of infecting susceptible animals, and, in short, 



