x,B,4 Crowell: Pathologic Anatomy of Bubonic Plague 259 
AUTHOR’S CLASSIFICATION 
From a study of my cases and those in the literature it seems 
sufficient from the pathologic standpoint to recognize only the 
two main types of plague: namely, the primary bubonic and 
the primary pneumonic types. These two types appear to me to 
include all cases of the disease. If it be desirable to subdivide 
the types in order to emphasize the fact that the alterations and 
symptoms do not always follow the same course, they may be 
so subdivided as to give prominence to the features most com- 
monly encountered. This subdivision will be more of value to 
enable one unfamiliar with the disease to recognize an atypical 
first case in a community, rather than as serving to indicate 
any essential difference in the pathologic processes occurring. 
Such a classification is here suggested. 
I. Primary bubonic plague. 
1. Uncomplicated bubonic plague. 
2. Bubonic plague (with early septicemia or without superficial bu- 
boes). 
3. Laila plague (secondary pneumonic type). 
4. Bubonic plague (secondary meningeal type). 
5. Bubonic plague (secondary cutaneous type). 
Ii. Primary pneumonic plague. 
To follow this classification to its logical conclusion, those 
types in which focal hepatic or renal lesions are present should 
also be separated, but this would serve only unduly to complicate 
the classification, especially as these types do not present prom- 
inent clinical differentiating characteristics. 
GENERAL DESCRIPTION OF THE PATHOLOGY OF BUBONIC PLAGUE 
The lesions of bubonic plague are due to Bacillus pestis and 
its endotoxins. The bacilli are introduced by the bite of an 
infected rat flea. A small papule may appear at the point of 
inoculation. The bacilli multiply and pass along the lymphatic 
vessels to the lymphatic glands into which they drain. The 
glands act more or less perfectly as bacterial filters and are at 
the same time usually profoundly altered by the action of the 
bacilli. These primarily affected glands are spoken of as the 
primary bubo of the first order, and from these the bacilli pass 
along the lymphatics to the next proximal glands, producing 
alterations in these glands which are, as a rule, of a lower grade 
of severity than in the primarily affected glands. The glands 
which are infected from the primary bubo of the first order by 
direct lymphatic continuity are spoken of as primary buboes 
of the second order. The bacilli, at some time in the disease, 
