AND CONTENTS OF THE MOUTH. 307 



elements spread in the saliva, of which a third part may be con- 

 sidered to be formed of microbes : ut tota aqua vivere videatur, as, 

 in his time, Leeuwenhoek wrote. The quantity of saliva which 

 continually moistens the mouth is not less than eight or ten 

 grammes ; therefore, we have three more grammes of germs and 

 elements, bringing the total up to 120 trillions. 



But we will not further trouble the reader by calculating the 

 other germs and elements lodged on the tongue, in the mucus of 

 the mouth and pharynx, and in the nasal cavities ; from which it 

 would result that the figures given above are not at all exaggerated. 



It is to be noted that we started with an average of 25 milliards 

 of bacteria per centigramme ; a figure twelve times under the cal- 

 culations of Naegeli — i.e., 30 milliards per milligramme, which 

 would make the mass of germs and elements of nose and mouth 

 upwards of 2 or j quadrilliojis. 



Besides, we must consider that Leptothrix lodges, as we have 

 demonstrated, even in the mouth of domestic animals. Now, the 

 mucus, saliva, breath, urine, faeces of these animals, jointly with 

 those of men, constitute, in their whole, an immense preserve. I 

 am led to believe that a great many germs and elements of Lepto- 

 thrix pass into the faecal matters alive. There is also incalculable 

 diffusion in the air, waters, and soil, especially in populous towns. 

 What wonder, then, that Perroncito has found such a large number 

 of bacteria in the dust of the streets ? We may, rather, contend 

 that such a dissemination of buccal microbes constitutes a sort of 

 cloud, which hardly permits external germs to penetrate. 



But let us return to the dissemination of Leptothrix in the 

 internal organs of the human economy. 



With regard to the digestive passages, the number of elements 

 carried there by the saliva must be fabulous, considering that in 

 the smallest drop myriads of them are to be found. Nor is it 

 presumable that their descent into the stomach should prove 

 inactive. 



The view that they are partakers in the transformation of ali- 

 ments is not new ; it goes as far back as Hallier, who considered 

 them necessary to the transformation, especially of starchy sub- 

 stances, not only in the stomach, but even in the mouth itself.* 



* Richter, Monograph quoted in the Bibliography, Part I. , Section B 2. 



