190 CLINICAL BACTERIOLOGY. 



bacteria is of most evanescent nature.* It does not with- 

 stand exposure to temperatures above 60 C. (140 F.), 

 drying and the like. If the cultures are boiled for several 

 hours, according to the view of R. Pfeiffer secondary toxic 

 substances are formed that manifest their activity only in 

 much larger amounts. The intoxication, however, pre- 

 sents the clinical features described. This intoxication with 

 the intracellular cholera-poison is remarkable for the rapidity 

 with which it appears, and for the entire absence of any 

 period of incubation, such as is commonly observed in con- 

 nection with the diphtheria-toxin and the tetanus-toxin. The 

 severity of the intoxication depends upon the amount of toxin 

 and the rapidity of absorption. The effects are most quickly 

 manifested when the poison is introduced directly into the 

 blood-stream. 



Epidemics of cholera arise, according to Koch, from 

 the first imported case, through whose dejections, con- 

 taining the bacilli, the disease is spread. The type of 

 distribution may be of two kinds. The disease may spread 

 in foci : a member in the family of the patient first attacked 

 is seized, then others, then another family in the same house, 

 a neighbor, a stranger accidentally present in the house, 

 the laundress to whom the linen from the first case is sent ; 

 in this way each disease-focus gives rise to another, and all 

 together form a closed chain. In every instance infection 

 has taken place through contamination with the dejections 

 of an earlier case. Often enough the connection of the 

 individual cases with one another is not demonstrable. 

 Thus, for instance, insects may carry the disease-germs 

 great distances and deposit them upon articles of food that 

 seemingly have in no way come in contact with a focus 

 of disease ; or apparently healthy individuals from the 

 neighborhood of the person first attacked may disseminate 

 the germs through their infected dejecta. 



On the other hand, the outbreak of the disease may take 

 place in an explosive manner, large numbers of cases appear- 

 ing equably and simultaneously throughout a town or a 

 city. This occurs when the water, whether delivered 

 through conduits or obtained from streams, is infected by 

 cholera-dejections, and the germ is thus capable of being 

 equably spread over the entire city, and carried into every 



* The poison can also be expressed from the bodies of the bacteria accord- 

 ing to the method of E. Buchner. (See foot-note, p. 179.) 



