172 MICBO-OKGANISMS AND DISEASE. [CHAP. 



phenol, and others, which are produced in the course of 

 putrefaction of proteids, have a most detrimental influence 

 on the life of many micro-organisms, as has been shown by 

 Wernich and others (see Antiseptics). 



It is not well known whether in all or in some of these 

 instances the organisms produce the chemical effects by creating 

 a special zymogen or ferment, and by this create the" chemical 

 disturbance, or whether they merely dissociate the compounds 

 by abstracting for their own use certain molecules ; but this 

 much is known, that in consequence of this chemical disturb- 

 ance definite chemical substances are produced. It is quite 

 possible that the pathogenic, like the zymogenic, organisms 

 have this special character, that if the soil (animal body) con- 

 tains a certain chemical substance, they are capable of growing 

 and thus capable of producing a definite zymogen or ferment. 



In many cases of putrefactive and zymogenic organisms a 

 definite soil may be capable of furnishing suitable material for 

 various organisms at the same time ; as a matter of fact this is 

 what one constantly meets with in ordinary putrefaction of 

 vegetable and animal matter, which teem with various species 

 of micro-organisms. But as a rule it will be observed that one 

 species is more apt to find a suitable soil in this substance than 

 others ; and then it will be found that this one organism, above 

 all others, grows more numerously ; and when it has done 

 growing, that is, when it has exhausted its own peculiar 

 pabulum, another organism, not dependent on this, but on 

 some other substance still present, makes a good start and 

 multiplies accordingly. Thus one finds constantly that, a 

 fluid, supposing it contains a variety of proteids, carbohydrates, 

 and salts, having become infected with micrococcus, and 

 various species of bacilli, in the first days or weeks chiefly 

 micrococci are present ; afterwards when the micrococci have 

 done multiplying and sink to the bottom of the fluid, this 

 latter gradually becomes filled with a variety of bacilli. Or if 

 micrococcus and bacterium termo be sown at the same time in 

 a suitable fluid, we find that at first only the bacterium termo 

 increases rapidly ; afterwards, when this has ceased multiply- 

 ing, the micrococcus takes the field. In still other cases, as 

 in putrid blood, exudation fluid, particularly in putrefying 

 solid parenchymatous or other substances, various kinds of 

 micro-organisms grow on simultaneously in different parts of 

 the material. 



The same holds good for the zymogenic organisms. A 

 solution containing sugar is a very fit soil for saccharomyces ; 

 when this has exhausted the material, i.e. when all the sugar 



