Fermentation and Kindred Phenomena. 105 



Organisms present in the system in health. — As the air we 

 inhale, the food we eat, and the water we drink, usually teem 

 with organisms, we are constantly introducing myriads of these 

 minute beings into our systems. Indeed, Miquel estimates the 

 number of spores introduced into the mouth at 300,000 a day ! 

 The fact would lose some, at least, of its repugnance if we were 

 assured that when once introduced they would perish, but such 

 is not the case, as any one can see for himself by examining a 

 droplet of saliva under the microscope, when it will be found to 

 swarm with all kinds of organisms, micrococci, bacilli, spirilla, 

 leptothrix, &c. In fact the entire track of the alimentary canal 

 appears to be a kind of garden in which organisms find a suitable 

 soil for their growth and development. It has even been 

 asserted that certain species aid in the processes occurring 

 within our bodies, and assist digestion, &c. Thus we are sur- 

 rounded by an invisible host of organisms, some deadly, some 

 possibly of service to us. We offer admittance to all, but we 

 expect the deadly not to enter, and broadly speaking we are 

 immune from them. The doctor can enter a fever ward with- 

 out infection. A family may breathe the same air and only one 

 of its members is stricken with consumption. A Sister Dora 

 (and for that matter many a physician whose name we never 

 hear of) can suck a tracheotomy tube, and yet without catching 

 diphtheria. We are almost confident now that in each of these 

 cases a disease organism enters the systems of all concerned. 

 11 Two women shall be grinding at the mill, one shall be taken, 

 and the other shall be left." At present I believe no satisfactory 

 explanation can be given of immunity. 



Let me return for a moment to the organisms present in the 

 mouth. Adhering to the teeth are always to be found thread- 

 like organisms called leptothrix buccalis. They are supposed to 

 cause the decay of teeth, and there can be no doubt that micro- 

 scopic examination shows that the decayed parts are full of organ- 

 isms. Another very singular fact connected with the organisms 

 found in the mouth, is that very often virulent species are present, 

 that is to say human saliva when injected into healthy animals, 

 such as rabbits, produces grave affections often terminating in 



