44 JOURNAL OF THE [March, 



line. In acid gelatine it produces carbonic acid, but in alkaline 

 no bubbles are formed, because a combination with the base 

 occurs. It begins to develop at a temperature of about 6°, and 

 the development continues up to 45°. At first, we observe 

 some very short rods, but later on, after the liquid has become 

 impoverished, we find elongated bacilli only. When the tem- 

 perature is sufficient, these form a superficial veil wherein we 

 often find very long filaments. The spores make their appear- 

 ance at the centre of each articulation soon afterwards, and 

 quickly drop off. They are easily distinguished in a prepara- 

 tion, since they are not colored by aniline. These spores are 

 killed only at a temperature of 100°, prolonged for at least ten 

 minutes. The sporeless rods, also, withstand very high tem- 

 peratures, and it is certain that they survive at a depth of more 

 than 7 or 8 millimetres in the bread, after the latter has been 

 baked. 



When we eat a little bread, then, we swallow myriads of living 

 bacilli. These are not destroyed in the human stomach, but, 

 on the contrary, find in the alimentary canal an abundance of 

 albuminoid and starchy substances for their nourishment. 

 Owing to their being adapted to both acid and alkaline media, 

 and to their property of living with or without air, they must 

 contribute towards digestion in man's alimentary canal. 



It is this same species of bacillus that, with a few others, 

 works in night-soil, and renders organic residua fit for the 

 nourishment of the plants of our fields and gardens. 



A few words as to bread made with yeast : As a matter 

 of fact, there is no bread free from bacteria, since germs always 

 exist in the flour used. For the same reason, we never have 

 any bread made exclusively with yeast. In Belgian bread, fer- 

 mentation is induced by Saccharomyces cerevisia. The phenom- 

 enon is the same as with the bacillus, save that it proceeds 

 much more rapidly. Thus, it takes six or seven hours to pre- 

 pare bread with leaven, while with yeast we in two hours ob- 

 tain a dough that is fit for baking. Nevertheless, we may ask 

 whether this substitution of the Saccharomyces for the Bacillus 

 can be done without danger, and whether the one is just as 

 well adapted as the other for panary fermentation. Aside from 

 the phenomenon of disengagement of carbonic acid, common to 

 all living beings, we have to consider the physiological action 



