20 



guinea pigs, produces a septicaemia, yet in man, under natural 

 conditions of infection, it generally leads to a local infection of 

 the lungs — lobar pneumonia. We have in another previous bulletin^ 

 called attention to the fact that all observations made on men show- 

 that the plague bacillus is not present at all early in the course of 

 the disease in the general blood circulation. Our histologic exam- 

 inations have further demonstrated that as a rule plague bacilli 

 are either found not at all in the vascular system or are present in 

 such very small numbers that an agonal or post-mortem invasion 

 suggests itself. 



It appears reasonable to limit the classification "septicgemia" 

 to those infections in which a multiplication of the infecting micro- 

 organisms obviously takes place in the general blood circulation. 

 During the last few years a valuable diagnostic method of blojd 

 examination in acute infectious disease has been used quite exten- 

 sively. Its results, however, have led to a misrepresentation of the 

 character and classification of some diseases. This method is 

 practiced as follows: From 1 to 5 cubic centimeters of blood, for 

 instance, in a case of pneumonia or typhoid fever, are drawn 

 from a vein and introduced into a culture flask containing from 

 50 to 300 cubic centimeters of nutrient broth. If now a pneumono- 

 coccus or typhoid growth develops, it is concluded that there is in 

 this case a general infection of the blood. But what does it really 

 mean if 1 to 5 cubic centimeters of blood do contain a few bacilli 

 w^hich develop and multiply under the most favorable artificial 

 conditions, conditions entirely different from those which prevail 

 in the live, undiluted circulating blood? It certainly does not 

 mean that these same micro-organisms could and would multiply 

 in the circulating blood in the presence of antibodies and of many 

 intact leucocytes. As it w^ould be wrong to classify typhoid fever 

 as a septicemia, because typhoid bacilli enter the blood from the 

 internal lymphatics, so it is wrong to classify ordinary bubonic 

 plague as a septicaemia because some bacilli invade the blood from 

 the infected lymphatics. If we do want to take cognizance of the 

 frequency and of the extent of the hemorrhages in plague, we may 

 -define it as an infectious disease with general hemorrhagic toxaemia. 



It was necessary early to enter into the discussion of this point 



^ Herzog and Hare : Does Latent or Dormant Plague Exist Where the 

 Disease is Endemic? Bulletin B. of G. L., Biological Laboratory, No. 20, I. 



