538 BACTERIOLOGY. 



microscopically such marked divergencies are seen that 

 we are still in doubt as to the existence of a common 

 factor. In the case of anthrax, a true septicsema, the 

 blood current is the seat of activity of the exciting 

 bacteria, and beyond congestion, enormous numbers of 

 bacteria in the blood vessels and the escape of serum 

 into the tissues (oedema), little else is to be seen to 

 account for death. On the other hand, in the case of 

 miliary tuberculosis, even though the involvement of 

 the organs may be general, there is no similar invasion 

 of the blood stream. The tubercles are circumscribed, 

 are often surrounded by healthy tissue and, though 

 obviously distributed throughout the body from a 

 primary focus through the agency of the circulating 

 fluids, each tubercle may nevertheless be regarded as a 

 local infection. There is, however, a conspicuous dif- 

 ference between the lesions found here and those seen 

 in anthrax. The lesion of tuberculosis, the tubercle, is 

 always characterized by tissue death at and about its 

 centre, i. ., where the bacilli are located, even in the 

 earliest stages of its development. 



In our autopsy on the animal dead of diphtheria we 

 observe conditions that are unlike those noted in both 

 anthrax and tuberculosis. There is neither an invasion 

 of the vascular system nor a distribution of conspicuous 

 pathological foci throughout the body. The bacteria 

 are as a rule confined to the primary site of invasion 

 and when found in distal organs are only there in 

 small numbers and give no evidence of an effect upon 

 the tissues immediately surrounding them. 



Thus far, as a result of this review, we have two 

 points in common to the three distinct diseases, viz . 



