6 14 Asiatic Cholera 



is lower than the surrounding solid portions, and the growth ap- 

 pears to be surmounted by an air-bubble. 



The luxuriant development of the spirilla in the hquefying gelatin 

 is followed by the formation of considerable sediment in the lower 

 third or half of the liquefied area. This sohd material consists of 

 masses of spirilla which have probably completed their Ufe-cycle and 

 become inactive. Under the microscope they exhibit the most 

 varied involution-forms. The liquefaction reaches the sides of the 

 tube in from five to seven days, but is not complete for several weeks. 



Agar-agar. — When planted upon the surface of agar-agar the 

 spirilla produce a grayish-white, shining, translucent growth along 

 the entire Hne of inoculation. It is in no way pecuUar or char- 

 acteristic. The vitahty of the organism is retained much better 

 upon agar-agar than upon gelatin, and, according to Frankel, the 

 organism can be transplanted and grown when nine months old. 



Blood-serum. — ^The growth upon blood-serum is also without 

 distinct pecuUarities; gradual Hquefaction of the medium occurs. 



Potato. — Upon potato the spirilla grow well, even when the 

 reaction is acid. In the incubator, at a temperature of 37°C., a 

 transparent, slightly brownish or yellowish-brown growth, somewhat 

 resembUng that of glanders, is produced. It contains large numbers 

 of long spirals. 



Bouillon. — In bouiUon and in peptone solution the cholera organ- 

 isms grow well, especially upon the surface, where a folded, wrinkled 

 pelhcle is formed, the culture fluid remaining clear. 



Milk. — In milk the growth is luxuriant, but does not usually 

 alter its appearance. The life of cholera organisms in milk is, how- 

 ever, rather short-lived, for when the acidity that invariably develops 

 reaches a certain point, they die out. 



Vital Resistance. — Although an organism that multipUes with 

 great rapidity under proper conditions, the cholera spirillum does 

 not possess much resisting power. Sternberg found that it was 

 killed by exposure of 52°C. for four minutes, but Kitasato found that 

 ten or fifteen minutes' exposure to ss°C. was not always fatal to 

 it; 6o°C. maintained for thirty minutes is certainly fatal. In 

 a moist condition the organism may retain its vitality for months, 

 but it is very quickly destroyed by desiccation, as was found by Koch, 

 who observed that when dried in a thin film its power to grow disap- 

 peared in a few hours. Kitasato found that upon sUk threads the 

 vital ty might be retained longer. Abel and Claussen* have shown 

 that it does not live longer than twenty or thirty days in fecal matter, 

 and often disappears in from one to three days. Zeatogorofff 

 found that if air was excluded from the fecal matter, the organisms 

 might remain alive for nine months. The organism is very suscep- 

 tible to the influence of carbolic acid, bichlorid of mercury, and other 



* "Centralbl. f . Bakt. u. Parasitenk.," Jan, 31, 1895, vol. xvii, No. 4. 

 t "Centralbl. f. Bakt. u. Parasitenk.," 1911, LViii, 14. 



