184 Chapter VII 



now ask ourselves whether the same substance acts also on micro- 

 organisms. 



For more than fifteen years a study of the bactericidal power of 

 the blood and other fluids drawn from the animal organism has 

 been carried on. Based on the not very definite results of Traube 

 and Gscheidlen 1 , Fodor 2 drew attention to the property of the de- 

 fibrinated blood of the rabbit to destroy the bacteria sown in it. 

 Under the inspiration of Fliigge 3 , Nuttall 4 carried out a whole series 

 of experiments on this bactericidal property of defibrinated rabbit's 

 blood, of the aqueous humour, and of some other fluids. After 

 confirming Fodor's general result, Nuttall went further and showed 

 that the bactericidal power of the fluids is due to a substance of 

 undetermined nature which is destroyed by heating to 55 C. for 

 one hour. This discovery was confirmed by a large number of 

 observers, and soon became an accepted fact. 



Fliigge now considered that he could base a theory of immunity 

 on the presence of the bactericidal substance of the body fluids. 

 Bouchard 6 and his school adopted and developed this view, especially 

 with reference to researches on the microbicidal power of blood 

 [195] serum. Buchner 6 soon came forward as the chief advocate of this 

 theory, and enriched it by numerous investigations carried out by 

 himself or along with collaborators in his school at Munich. It is to 

 him that we owe the suggestion of the term alexine (protective 

 substance) to designate the bactericidal substance of blood serum 

 and other fluids of the animal organism which are capable of 

 killing micro-organisms. Buchner determined the conditions under 

 which alexine acts best as a bacterial poison and developed the 

 humoral theory of natural immunity, according to which the latter 

 is reduced to the bactericidal property of the body fluids. 



As the postulates of this theory are often not in accord with the 

 real facts, as Lubarsch 7 , especially, has demonstrated in many of his 



1 Jahresb. d. schles. Gesellsch.f. vaterl. Cultur, Breslau, 1874. 



2 Deutsche med. Wchnschr., Leipzig, 1886, S. 617 ; 1887, S. 745. 



3 Ztschr.f. Hyg., Leipzig, 1888, Bd. iv, S. 208. 



4 Ztschr.f. Hyg, Leipzig, 1888, Bd. iv, S. 353. 

 " Les microbes pathogenes," Paris, 1892. 



6 Arch.f. Hyg., Munchen u. Leipzig, 1890, Bd. 10, S. 84; CentralU.f. Bakteriol. 

 u. Parasitenk., Jena, 1889, Bd. v, S. 817, and Bd. vr, SS. 1, 561; 1890, Bd. vin, 

 S. 65. 



7 CentralU.f. Bakteriol. u. Parasitenk., Jena, 1889, Bd. vi, S. 481; Ztschr.f. 

 klin. Med., Berlin, 1891, Bde xvni, xix. 



