188 Chapter VII 



arguments and must be regarded as generally abandoned, because 

 it is now completely out of accord with well-established facts. Thus, 

 various osseous fishes, in spite of the total absence of eosinophile 

 or pseudo-eosinophile granules are none the less capable, thanks to 

 their leucocytes, of destroying a large number of pathogenic micro- 

 organisms (Mesnil, I. c.\ 



A similar theory was enunciated by H. Buchner 1 , though he holds 

 that it is not the eosinophile leucocytes only that secrete the bacteri- 

 cidal substance, but the leucocytes in general. Being attracted to 

 the point menaced by the micro-organisms, these cells secrete 

 their bactericidal product, which diffuses into and along with the 

 plasma of the exudations and of the blood. In these fluids the 

 micro-organisms undergo a more or less complete destruction, or 

 at least severe injury which renders them more susceptible to the 

 attack of the phagocytes. At the International Congress of Hygiene, 

 held at Budapest in 1894, Buchner proclaimed the thesis that "the 

 leucocytes fulfil an important function in the natural defence of the 

 organism... by means of soluble substances which they secrete." 

 Later, his pupils, Hahn 2 and Schattenfroh 3 , endeavoured to support 

 [199] this theory by exact experiments, but they found it impossible to do 

 this at all satisfactorily. Later, another of Buchner's pupils, Lascht- 

 schenko 4 , published a paper in which he maintains that he has found a 

 convincing argument. It is as follows. A blood serum, by itself void 

 of bactericidal property, some minutes after white corpuscles from 

 another species of mammal have been added to it acquires this pro- 

 perty. Thus the rabbit's leucocytes added to dog's serum imme- 

 diately give to it the bactericidal power, so long as a large number 

 of cells remain alive and motile. But when the leucocytes of the 

 same species are added to rabbits' serum the fluid becomes no more 

 bactericidal than before. The same result may be obtained by mixing 

 rabbits' leucocytes with the blood serum of the horse, pig and other 

 species. Laschtschenko concludes from these observations that the 

 vital secretion of the bactericidal substance by the leucocytes of the 

 rabbit takes place when they are irritated by the serum of a different 

 species. As an analogous effect has been observed with mixtures of 



1 Munchen. med. Wchnschr., 1894, S. 717 and 1897, S. 1320. 



2 Arch. f. Hyg., Munchen u. Leipzig, 1895, Bd. xxv, S. 105 ; 1897, Bd. xxvui, 

 S. 312. Berl klin. Wchnschr., 1896, S. 864. 



3 Arch. /. Hyg., Munchen u. Leipzig., 1897, Bd. xxxi, p. 1 ; 1899, Bd. xxxv, 

 S. 135. Munchen. med. Wchnschr., 1898, SS. 353, 1109. 



4 Arch.f. Hyg., Munchen u. Leipzig, 1900, Bd. xxxvn, S. 290. 



