PROTECTIVE INOCULATIONS. 287 



bits and to fowls. lu the larger animals pulmonary and intestinal 

 lesions are developed, and in swine a diffused red color of the skin, 

 similar to that observed in the disease known in Germany as Schicein- 

 erothlauf (Fr. rouget) is sometimes seen. 



According to Baumgarten, bacilli from JVildseiiche or from Rinder- 

 seaclie inoculated into swine give rise to fatal Schweineseuche, and 

 bacilli from any of these forms of disease, when inoculated into pig- 

 eons, produce characteristic fowl cholera ; but the bacillus as obtained 

 from Schweinesucheoi W&dseucke is not fatal to chickens, and the ba- 

 cillus from Schweineseuche is fatal to guinea-pigs, which have but 

 slight susceptibility to the bacillus of rabbit septicaemia. Notwith- 

 standing these differences, he agrees with Hueppe in the view that the 

 bacilli from the various sources mentioned are specifically identical; 

 although evidently, if this view is adopted, we must admit that varie- 

 ties exist which differ somewhat in their pathogenic power. 



In this volume this bacillus is described under the name Bac'Jlus 

 septiccemice hcemorrhagicce, first proposed for it by Hueppe. In the 

 present chapter we shall give an account of the experimental evidence 

 relating to protective inoculations in various animals, with the differ- 

 ent varieties of the bacillus in question which have been encountered. 



It seems probable that the same bacillus was the cause of the fatal 

 form of septicaemia studied by Davaine, which resulted from the in- 

 oculation of susceptible animals with putrefying blood. These ex- 

 periments by the distinguished French physician constitute an im- 

 portant part of the pioneer work in this field of research. They were 

 commenced in 1868, and are published in the Bulletin of the Academy 

 of Medicine (seance of Feburary 18th, 1879). 



Davaine, in the paper referred to, calls attention to the fact, devel- 

 oped by his experiments, that there is a great difference in the resist- 

 ing power of different animals to the form of septicaemia which had 

 been the subject of his investigations. Thus the rabbit succumbed 

 when inoculated with a millionth part of a drop of blood, while guinea- 

 pigs and dogs remained unaffected by such small doses. With refer- 

 ence to the specific cause of the form of septicaemia studied by him, 

 Davaine says : 



"The virus is one of the bacteria of putrefaction. I say 'one of the bac- 

 teria,' because there is reason to believe that there are among these minute 

 organisms numerous species which do not all develop at the same time when 

 they are present in various media." 



Davaine also discovered the fact that infection depends, within 

 certain limits, upon the quantity of bacteria introduced into the tis- 

 sues. He says : 



