388 BACTERIOLOGY. 



those biological and morphological features of the organ- 

 ism that appear most quickly under artificial methods 

 of cultivation, and which, at the same time, may be 

 considered as characteristic of it, viz., its peculiar mor- 

 phology and grouping; the much greater rapidity of its 

 growth over that of other bacteria with which it may 

 be associated; the characteristic appearance of its col- 

 onies on gelatin plates and of its growth in stab-cultures 

 in gelatin; its property of producing indol and coinci- 

 dently nitrites in from six to eight hours in peptone 

 solution at 37 to 38 C. ; and its power of causing the 

 death of guinea-pigs in from sixteen to twenty-four 

 hours when introduced into the peritoneal cavity, death 

 being preceded by symptoms of extreme toxaemia, char- 

 acterized by prostration and gradual and continuous 

 fall in the temperature of the animal's body. 



In a publication made by Koch 1 he called atten- 

 tion to a plan of procedure that is employed in this 

 work in the Institute for Infectious Diseases at Ber- 

 lin. In this scheme the points that have been enume- 

 rated are taken into account, and by its employment 

 the diagnosis can be established in the majority of 

 cases of Asiatic cholera in from eighteen to twenty-two 

 hours. In general, the steps to be taken and points to 

 be borne in mind are as follows: the material should 

 be examined as early as possible after it has been passed. 



I. Microscopic examination. From one of the small 

 slimy particles that will be seen in the semi-fluid evac- 

 uations prepare a cover-slip preparation in the ordinary 

 way and stain it. If, upon microscopic examination, 

 only curved rods, or curved rods greatly in excess of all 



* Zeitschrift fur Hygiene, 1893, Bd. xiv. 



