436 



PLAGUE. 



important points. They cultivated the same organism from a 



large numberof 



^'-'5 *H/Jf *i'dl^ cases of plague, 



i'lHlfelVltl fjr^/ and reproduced 



*< ^ i?J5& MS, the disease in 



*WC '^^^4 susceptible ani- 



mals by inocu- 

 lation of pure 

 cultures. It is 

 to- be noted 

 that during an 

 epidemic of 

 plague, some- 

 times even pre- 

 ceding it, a high 

 mortality has 

 been observed 

 among certain 

 animals, espe- 



FlG. 147. Film preparation from a plague bubo showing cla U v ra -tS and 



enormous numbers of bacilli, most of which show well-marked bi- mice, and that 



polar staining. ,- , , , . 



Stained with weak gentian-violet. X 1000. 



of these ani- 

 mals found dead in the plague-stricken district, the same bacillus 

 was obtained by Kitasato and ..- 



also by Yersin. r . \ v / , '- 



Bacillus of Plague. Micro- .v - ' v y ""*** ^ ~\~*\ 

 scopical Characters. As seen ' .' \ '4\*\ - '% 

 in the affected glands or buboes - -, % 1 * \ ! < > ^ 



in this disease, the bacilli . -^' ^ ^ \*\ ' ^"' 

 are small oval rods, somewhat * v> ''*'{;v * -^ 

 shorter than the typhoid bacil- . ,\ > x +'-.'*' , \ '/ ' ^' '* 

 lus, and about the same : \ * ' % %% 



thickness (Fig. 148), though 

 considerable variations in size 

 occur. They have rounded 

 ends, and in stained prepara- 



'/ ^ - v . \ 



xx--~\ 

 .*<^- ... - 



FlG . I48 ._ Bacillus of plague from a 



tions a portion in the middle of y un s culture on agar. 



Stained with weak carbol-fuchsin. Xiooo. 



the bacillus is often left uncov- 



ered, giving the so-called " polar staining." In films from the 



