ASIATIC CHOLERA. 181 



the serum of those immune to typhoid fever does not 

 possess antitoxic properties. The therapeutic experiments 

 with typhoid-cultures exposed to a temperature of 60 C. 

 (140 F.) that have thus far been made upon human beings 

 have also failed. This want of success can not be opposed 

 to the possibility already suggested of prophylactic immuni- 

 zation by means of dead bacilli, inasmuch as the already 

 diseased and poisoned organism may react differently than 

 the healthy body to injections of typhoid poison. 



ASIATIC CHOLERA. 



The exciting agent of Asiatic cholera is the comma- 

 bacillus discovered by Koch in 1883. 



The cholera-bacilli are more or less markedly curved rods 

 (vibrios) , from one-half to at most two-thirds as large as tubercle- 

 bacilli (from 0.8 to 2 /a), although thicker than these. The 

 comma-form is not well defined in all bacilli. Every preparation 

 contains forms, especially the quite young bacilli, that appear as 

 simple, straight, extended bacilli. The most characteristic and 

 typical commas are present in freshly made artificial cultures. 

 Besides, the form of the growing vibrios varies in accordance with 

 their source in one or another epidemic. In certain epidemics 

 the cholera-bacteria assume throughout an almost straight form. 

 Frequently the comma-bacilli are arranged in pairs ; when two 

 commas are so applied to each other that the corresponding 

 curves are opposed, the so-called S-form results. 



If in the growth of the vibrios the individual newly formed 

 bacteria adhere to one another after division, the so-called 

 cholera-spirilla result. Though observed very seldom in the 

 dejections of cholera-patients, the spirilla occur frequently in 

 artificial cultures, especially when these have become old, the 

 nutrient material exhausted, or if an antiseptic in dilute con- 

 centration (as, for instance, alcohol) has been added. The 

 spirilla occur with especial frequency in the peritonitic exudate 

 of guinea-pigs inoculated with cholera-bacilli. The spirilla are 

 generally looked upon as involution -forms, principally because 

 they are thicker in cultures than the young individual commas. 

 The cholera-vibrios exhibit extraordinarily active motility. This 

 is especially noticeable in the hanging drop, in which their ap- 

 pearance suggests a swarm of dancing gnats. This motility is 

 dependent upon the presence of terminal flagella that can be 

 readily demonstrated at one extremity by means of L6 filer's 

 method of staining. 



