324 



MANUAL OF BACTERIOLOGY. 



followed by considerable constitutional disturbance. This 

 method seems likely to be of considerable value. 



Yersin and others have prepared protective sera on the same 

 general principles used in making other sera for effecting pas- 

 sive immunity. The results so far obtained with these sera 

 are not especially encouraging.* 



Fig. 77. — Bacillus aerogenes capsulatus, smear preparation from 

 rabbit's liver.. (X 1000.) 



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 dur- 

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

 the localities of importance to us it has recently visited the 

 Phihppine Islands, California and Mexico. It has ravaged 



*Giinther. Loc. cit. p. 630. 



