AXD OF EXPOSED MUCOUS MEMBRANES. 575 



In diseased conditions these are more numerous than in health, but 

 the pus cocci are not infrequently found in healthy eyes. 



As bacteria are constantly present in the air, they are necessarily 

 deposited upon the moist mucous membrane of the nose during in- 

 spiration. Indeed, it would appear as if an important function of 

 this extended mucous membrane is to purify the air from suspended 

 particles, and it has been shown by experiment that expired air is 

 practically free from bacteria. The greater number of those con- 

 tained in inspired air are deposited upon the mucous membrane of 

 the anterior and posterior nares. In culture experiments made by 

 Von Besser, Wright, and others the nasal mucus was found to con- 

 tain a great variety of bacteria; among others the pus cocci were 

 frequently found by both of the observers mentioned. In eighty-one 

 cases Von Besser found the "diplococcus pneumonise" fourteen 

 times, Staphylococcus pyogenes aureus fourteen times, Streptococ- 

 cus pyogenes seven times, and Friedlander's bacillus twice. Twenty- 

 eight of the cases examined were convalescents in hospital ; among 

 these the pathogenic species mentioned were found less frequently 

 than in other individuals. The following non-pathogenic species 

 were isolated : Micrococcus liquefaciens albus in twenty-two cases, 

 Micrococcus albus in nine cases, Micrococcus cumulatus tenuis in 

 fourteen cases, Micrococcus flavus liquefaciens in three cases, Bacil- 

 lus striatus albus in ten cases, etc. 



Paulsen (1890) made thirty-one cultures in nutrient gelatin from 

 sixteen persons and thirty-three in nutrient agar from twenty-two 

 persons, with the following result : Eleven remained sterile, nine- 

 teen showed not more than ten colonies, sixteen less than one hun- 

 dred, twelve more than one hundred, and in six the number was so 

 great that they could not be counted. Micrococci were more nu- 

 merous than bacilli ; of these a " sulphur-yellow coccus" in tetrads 

 was found in eight individuals. Various species of liquefying cocci, 

 resembling the pus cocci, were isolated, but the conclusion was 

 reached that none of these were identical with the staphyloccoci 

 of pus, which Von Besser and Wright both found in a considerable 

 proportion of the culture experiments made by them. 



Very extended researches have been made with reference to the 

 bacteria present in the human mouth, which show that numerous 

 species are constantly present in the buccal secretions and upon the 

 surface of the moist mucous membrane. Some of these are occa- 

 sional and accidental, while others appear to have their normal habi- 

 tat in the mouth, where the conditions as to temperature, moisture, 

 and presence of organic pabulum are extremely favorable for their 

 development. A minute drop of saliva spread upon a glass slide, 

 dried, and stained with one of the aniline colors, will always be 



