DISTRIBUTION AND HABITAT OF THE BACTERIA. 723 



infection which are constantly present and very evident, 

 always search for the ominous glass of "impure " water 

 which has in their opinion caused the disease. 



Large numbers of bacteria are also present on the Bacteria on 

 surface of the human body. The most various forms of the 06 



bacteria have already been demonstrated on the skin, in 



the sweat from the feet and axilla, &c. It is evident On the skin. 



from the researches of Forster,* that in spite of appa- 



rently careful washing, bacteria still adhere to and 



retain their vitality in the folds of the skin of the finger 



and under the finger nails ; he found that, even after 



cleaning the hands with brushes, water, and soap, if the 



fingers were pushed into nutrient jelly a varying number 



of bacterial colonies constantly developed. 



On the internal surfaces of the body still greater in the mouth. 

 numbers of bacteria are found. For a long time sapro- 

 phytes have been known to exist in the mouth, which 

 excite fermentations, and bear a distinct relation to 

 caries of the teeth (p. 391) ; various forms of pathogenic 

 bacteria have also been observed there. Thus Kreibohm 

 in a relatively small number of cultivations from the 

 secretions of the mouth has isolated four different forms 

 which cause septicaemia in animals (see p. 319) ; and 

 also the bacillus crassus sputigenus, which occurs com- 

 paratively frequently in man, which likewise causes 

 septic infection in some animals, and which produces in 

 its cultivations a violent poison, killing those animals 

 which are not susceptible to infection by intoxication if 

 introduced in large doses. This state of matters is 

 readily intelligible when one considers that in the cavity 

 of the mouth there exists a very suitable temperature, 

 and in the dead epithelium, &c., a good nutritive mate- 

 rial for the development of pathogenic bacteria. Hence 

 it is readily conceivable that parasitic bacteria, which 

 require a special point for their invasion of the body, can 

 live for a time as epiphytes, till they find an opportunity 

 of entering the body, and thus the occurrence of an infec- 



* Centralb. < Uin. med., 1835, Nr. 18. 



