BACILLUS ANTHRACIS. 239 



and penetrate through the uninjured mucous mem- 

 brane. 



In the body of living animals the bacilli multiply only Conditions of 



,. J , 5> r j j 8 P re t'orma- 



by fission, and never form spores. These arise on dead tion. 

 nutritive substrata, but only under definite conditions, 

 among which a suitable temperature is the most impor- 

 tant. The highest limit of temperature is about 43 

 C. ; the lowest from 12 to 18 C. ; below 12 C. neither 

 growth of threads nor spore formation seem to occur. 

 Hence if the bodies of animals which have died of 

 anthrax are buried very deeply in the soil, where in our 

 climate there is a constant temperature below 12 C., 

 spore formation does not occur, and the bacilli them- 

 selves speedily die without having passed into a resting 

 form. Pasteur's assertion that the bacilli or their spores 

 are preserved in the buried bodies, and that they are 

 then brought up to the surface of the soil by means of 

 worms, is thus wholly improbable. On the contrary, we 

 have to explain the occurrence of an epidemic of anthrax, 

 according to Koch, in the following manner : the germs Mode of 

 which are distributed since ancient times in marshy anthrax* 

 regions, on banks of rivers, &c., can again develop on bacilli - 

 suitable vegetable substrata, and there form new spores ; 

 these are carried to pasture lands by floods, and 

 thus become mixed with the fodder. This mode of 

 spread also explains the infection from the intestine, 

 which is much the most frequent mode observed. 

 Recently Schrakamp and Friedrich have mentioned the 

 possibility that the growth and development of the 

 anthrax bacilli may also occur in the upper layers of the 

 soil ; while Kitt regards cattle dung as the chief nutritive 

 substratum in which the development and spore formation 

 of the bacilli occurs in the regions infected by this dis- 

 ease. (See the chapter on the exciting agents of disease.) 



Of great scientific value is the discovery by Toussaint Artificial 

 and Pasteur that the anthrax bacilli can lose their patho- 

 genie properties by the moderate action of abnormally bacilli - 

 high temperatures, or of small doses of poisonous sub- 

 stances, while their morphological and biological cha- 

 racters remain otherwise unaltered. On the mode in 



