TEXT-BOOK OF BACTERIOLOGY. 149 



than the bacteria would have done. Yet it would be unwise to give 

 up in despair on account of the want of success hitherto secured. 

 The valuable results obtained by the purely empirical treatment of 

 malaria with quinine and of syphilis with mercury encourage us 

 to persevere and warn us against a too early abandonment of our 

 efforts. 



Although we have not yet succeeded in discovering with com- 

 plete certainty the exciting causes of these two diseases, yet there 

 is every reason to believe that they belong to the class of diseases 

 occasioned by parasites of the lowest forms, and if chance has en- 

 abled us to find specific remedies for these evils, we may hope that 

 strictly methodical experiments and systematic investigation will 

 also lead to like success in other cases. 



That it is in reality possible to paralyze and get the mastery 

 over micro-organisms, even of the most dangerous kind, in the 

 bodies of susceptible animals, has been proved by the interesting 

 observations of Pawlowsky, of Bouchard, and more particularly of 

 Emmerich. These investigators succeeded in saving from almost 

 certain death rabbits inoculated with virulent anthrax bacilli, 

 by bringing a considerable quantity of erysipelas micrococci, of 

 green pus bacilli, or of Micrococcus prodigiosus into the circulation 

 either before or after the anthrax inoculation. The animals con- 

 tinued to live, but without immunity against a later inoculation 

 with anthrax, to which they regularly succumbed. 



Here, then, there was no acquired permanent immunity, but a 

 real cure of a parasitical affection, attained by the agency of a 

 second species of bacteria, and we have only to inquire how this 

 counter-effect is to be explained. 



That there exists a decided antagonism between certain micro- 

 organisms has been shown by the experiments of Soyka, Garre, 

 Freudenreich, and others. If sterilized gelatin be allowed to harden 

 on a glass plate and the surface of this solid culture medium be 

 planted with various kinds of bacteria by means of needle strokes 

 at short intervals from each other, after a few days it will be seen 

 that the expected growth here and there fails to make* its ap- 

 pearance. 



Further examination will show that the excretions of certain 

 bacteria act as a decided check to the development of certain 

 others, and sometimes even exercise a destroying influence and kill 

 the neighboring growth. 



He who would simply apply these facts to the living body would 

 find himself sometimes unpleasantly disappointed, for the living 

 tissue is no plate of gelatin and no test-tube. But for the explana- 



