xvii.] SEPTIC AND PATHOGENIC ORGANISMS. 155 



bottom of fluid broth, and which have been so accurately 

 described by Pasteur. 



Both the hay bacillus and the anthrax bacillus when growing 

 on gelatine mixtures liquefy the gelatine ; both when growing 

 in meat broth turn the at first colourless fluid in the course of 

 incubation to an amber, and further to a brown, tint. 



The hay bacillus is capable of thriving well in acid solutions, 

 it grows copiously in hay infusion, which is of a distinct acid 

 reaction ; the bacillus anthracis, although capable of making 

 a slight progress in acid hay infusion, does not get far, for 

 degeneration soon sets in ; it thrives best in neutral solutions. 

 Hay bacillus thrives also very well in neutral solutions. 



Buchner states, that by successive cultivation of bacillus 

 anthracis under constant variation of the nutritive material, 

 he saw it assume gradually the properties of hay bacillus. 

 Thus he saw that its mode of growth gradually changed, 

 inasmuch'as instead of forming, as the typical bacillus anthracis 

 does, fluffy convolutions at the bottom of the fluid-nourishing 

 medium, it gradually showed a tendency to stick to the glass 

 and to the surface of the fluid, and to form a sort of pellicle 

 just like the hay bacillus does. This I consider to be an 

 erroneous interpretation of an easily explained and simple 

 fact. It does not want any of the many successive generations 

 of bacillus anthracis, in which Buchner says he has achieved 

 this transformation, it simply requires two* nourishing fluids, 

 in both of which the bacillus anthracis will thrive well, but 

 which fluids differ in specific gravity. Let Buchner do as I 

 have done, let him take two test-tubes, both containing sterile 

 broth, but in one the broth concentrated, in the other dilute. 

 Let him inoculate the two test-tubes with bacillus taken from 

 the same blood, say of a guinea-pig dead of anthrax, let him 

 place them in the incubator at a temperature of 35 42 C. 

 After two or three days, and more decidedly later, he will 

 notice this very difference in the aspect of the cultures that he 

 lays so much stress on as indicating a change in the physiological 

 character of the bacillus. One test-tube, containing the dilute 

 broth, shows the typical fluffy convolutions at the bottom of the 

 fluid ; while the other, containing concentrated broth, shows a 

 distinct attempt at the formation of a pellicle. Let him now 

 take out a droplet from this second test-tube and inoculate 

 with it two test-tubes of the same nature as above, i.e. one 

 containing concentrated broth, the other dilute broth. After 

 two er three or more days of incubation he will find exactly 

 the same differences as above. 



Buchner states that the bacillus anthracis when carried 



