INFECTION AND INTOXICATION. 73 



and Schottelius have shown that the healthy animal is 

 born free from bacterial life. In its entrance into inde- 

 pendent existence, however, it is at once introduced to a 

 world of bacteria that fall upon the skin, to be caught by 

 hair or feathers, or to insinuate themselves between the 

 epithelial cells of the epidermis, are inhaled into the re- 

 spiratory passages, swallowed into the alimentary canal, 

 and find their way into the various openings of the 

 body, until each becomes a regular habitat for a number 

 of species. There being no hereditary transmission of 

 bacteria in health, the micro-organisms habitual to the 

 body are but accidental intruders that chance has brought 

 where moisture, heat, and nourishment have enabled 

 them to colonize. Upon investigation we further find 

 that the flora of each region is appropriate to the condi- 

 tions there existing, so that the feebly alkaline saliva 

 harbors quite a different flora from the acid secretions of 

 the vagina, etc. The greater number of bacteria thus 

 found inhabiting the body-surface and cavities are harm- 

 less, but many of those familiar to us as disease-producers 

 also occur. It therefore becomes quite evident that we 

 constantly carry the source of many of our ills with us. 

 Not all of these pathogenic parasites are attenuated, ex- 

 periment as well as experience indicating that they are 

 sufficiently virulent to await only the proper opportunity 

 to bring about their familiar lesions. 



a. Skin. — It would be as useless as it would be tire- 

 some to compile a list of the non-pathogenic bacteria that 

 may be found upon the skin. The very fact that the 

 skin surface is extensive, external, slightly moist, and 

 constantly in contact with external objects ought to be 

 sufficient guarantee that almost any bacterium may be 

 found upon it. 



Of the pathogenic organisms, it is probable that the 

 Staphylococcus epidermidis albus (Welch) is the most 

 widely distributed. The Staphylococcus pyogenes albus 

 and aureus are also quite common. Bordoni-Uffreduzzi 

 found that some of the odors of the skin are peculiar to 



