57° 



Asiatic Cholera 



water from polluted gutters; how they enter milk with water used 

 to dilute it; how they appear to be carried about in clothing and 

 upon food-stuffs; how they can be brought to articles of food by flies 

 that have preyed upon cholera excrement; and other interesting 

 modes of infection. The literature is so vast that it is scarcely 

 possible to mention even the most instructive examples. A bacteri- 

 ologist became infected while experimenting with the cholera spirilla 

 in Koch's^ laboratory. It is commonly supposed that the cholera 

 organism may remain alive in water for an almost unlimited length 

 of time, but experiments have not shown this to be the case. Thus, 

 Wolffhiigel and Riedel have shown that if the spirilla be planted 

 in sterilized water they grow with great rapidity after a short time, 





Fig. 236. — SpiriEum of Asiatic cholera, from a bouillon culture three weeks old, 

 showing long spirals. X 1000 (Frankel and PfeifiEer). 



and can be found alive after months have passed. Frankel, how- 

 ever, points out that this ability to grow and remain vital for long 

 periods in sterilized water does not guarantee the same power of 

 growth in unsterilized water, for in the latter the simultaneous 

 growth of other bacteria serves to extinguish the cholera spirilla 

 in a few days. 



Morphology. — The micro-organism described by Koch, and 

 now generally accepted to be the cause of cholera, is a short rod 

 I to 2 M in length and 0.5 m in. breadth, with rounded ends, and a 

 distinct curve, so that the original name by which it was known, the 

 "comma bacillus," applies very well. One of the most common 

 forms is that in which two short curved individuals are conjoined 

 in an S-shape. 



When the conditions of nutrition are good, multiplication by fission 

 progresses with rapidity; but when adverse conditions arise, long 



