BACTERIA IN INFECTIOUS DISEASES. 261 



of living animals. They are known to infest the 

 alimentary canal, and it is probable that the small- 

 est portion of hair or epithelium detached from 

 the surface of the body qf any one of the lower 

 animals would fertilize a culture-solution ; but 

 blood drawn from the veins with proper precau- 

 tions does not fertilize a sterilized culture-solution. 

 Koch says (I. <?.) "I have on many occasions exam- 

 ined normal blood and normal tissues by means 

 which prevent the possibility of overlooking bac- 

 teria, or of confounding them with granular masses 

 of equal size ; and I have never, in a single in- 

 stance, found organisms. / have, therefore, come to 

 the conclusion that bacteria do not occur in the blood, nor 

 in the tissues of the healthy living body, either of man or 

 of the lower animals" 



As an example of the development of putre- 

 faction, as a result of inoculation by a chemical 

 virus, we may refer to the recent experiments of 

 Weir Mitchell, and Eeichert, " On the Venom of 

 Serpents." These gentlemen find that venom 

 contains three proteids. One of these, venom 

 peptone, is not poisonous as a venom, but its in- 

 jection into the breast of a pigeon gives rise to 

 remarkable local effects. A lump forms, and with- 

 in forty-eight hours a gangrenous cavity is pro- 

 duced, from which putrefactive odors are given off. 

 That putrefaction here, as elsewhere, is produced 

 by the bacteria of putrefaction, there can be no 

 doubt; for no known proteid is capable of pro- 

 ducing putrefactive changes in a sterilized organic 



