266 MANUAL OF BACTERIOLOGY. 



An agglutination reaction has been described; but this is not 

 likely to be of great value in diagnosis. 



The period of incubation in this disease is from two to seven 

 days. It has occasionally appeared in civilized countries 

 during recent times, though not to a very serious extent. Among 

 the localities of importance to us it has recently visited the 

 Philippine Islands, California and Mexico. It has ravaged 



Fig. 72. — Bacillus aerogenes capsulatus, Smear Preparation from 

 Rabbit's Liver. (X 1000.) 



the southeastern part of Asia within a few years. In the Middle 

 Ages, and in succeeding centuries, it devastated many of the 

 countries of Europe, where it was one of the most important 

 of the pestilences that went in those days by the name of the 

 "plague." It appears to have been the disease known in 

 Enghsh history as the "black death."* 



* For further details concerning plague consult articles by Barker, Novy 

 and Flexner. Transactions of the Association American Physicians. 1902, 

 Calvert. American Medicine. January 24, 1903. 



