PHYSIOLOGY OF THE MICROBES 87 



tetanus bacillus, tetanolysin ; of the staphylococci, staphylo- 

 lysin ; of the cholera and pseudo-cholera vibrios, vibriolysin ; 

 of the streptococci, streptocolysin ; of bacillus pyocyaneus, 

 pyocyanolysin ; lysins also exist in the cultures of B. typhosus, 

 of fowl-cholera, of the anthrax bacillus and in the bacillus of 

 diphtheria (in this case doubtless in the body of the bacillus, 

 not excreted). 



The majority of the bacterial haemolysins are destroyed by 

 heating to 56° C. ; that of the bacillus of fowl-cholera, however, 

 is only destroyed at 70° C. ; while pyocyanolysin stands boiling 

 for a long time and is only destroyed in half an hour at 

 120° C. 



Along with these enzymes should be classed the lysins 

 which attack the leucocytes (leucocidine of Vandevelde) and 

 other bacteria (pyocyanase of Emmerich). 



Products of Cultures. Microbic Excretions. — A 

 medium in which a bacterial culture has grown contains bodies 

 which were not present before the inoculation. These are 

 products of the activity of the microbes in relation to their 

 food-stuffs; they do not come exclusively from the microbe 

 itself, but they are products of these and bear their mark. It 

 is often difficult to draw the line between true secretory 

 products, the diastases and toxins — and the residual substances 

 remaining after enzymatic action, the study of which ought to 

 be included with that of the fermentations and putrefactions — 

 and the excreta, the catabolic products, properly speaking. 



The distinctions which are currently drawn between these 

 products depend often on the purpose we have in view. We 

 stop a fermentation when it has reached the stage of the 

 products which are useful, as, for example, in the manufacture 

 of beer, wine, and cheese; if left to continue, the organic 

 matter breaks down finally to the simplest substances, water, 

 carbonic acid, and ammonia. In nature a ferment only ceases 

 when it has furnished the materials for a new fermentative 

 process. 



" A bacterial product is a substance incapable of being 

 attacked under the conditions of the experiment by the 



