154 MANUAL OF BACTERIOLOGY. 



The smegma of the external genitals contains numerous 

 bacteria, among which are frequently found bacilli which 

 retain their color after treatment with acids in the Gabbett 

 method for staining tubercle bacilli. It is uncertain whether 

 these, bacilli form a special group of organisms by them- 

 selves, having as one of their properties the power of re- 

 taining the stain after acids, or whether they are bacilli of 

 no particular sort, which resist acids after staining owing 

 to the oily material with which they have been impregnated 

 in this peculiar secretion. These organisms must be taken 

 into account in staining for tubercle bacilli, urine or other 

 secretions which might accidentally contain particles of 

 smegma. Usually the employment of alcohol after the acid 

 will remove the color from the smegma bacilli (Hueppe). 

 Sometimes smegma bacilli are as resistant as tubercle bacilli 

 to decolorizing agents (Welch) ; see page 44. Similar acid- 

 proof bacilli occur about the genitals of the domestic ani- 

 mals. 1 



The bacteria of the stomach and intestines are of great 

 interest and importance. The alimentary tract of new-born 

 infants and the meconium are sterile. In from four to 

 eighteen hours organisms begin to appear. They may 

 enter either from the mouth or the anus. There seems to 

 be no constancy in the nature of the forms which are found 

 at first, but their character depends upon the surroundings. 



The bacterial inhabitants of the stomach are less constant 

 than we shall find those of the intestines to be. Under 

 normal circumstances they seem to be those introduced 

 from the mouth. Different investigators, at all events, 

 have met with quite different species. It appears that the 

 hydrochloric acid (about 2 parts per thousand) present in 

 the gastric juice at the height of digestion possesses decided 

 germicidal properties. This germicidal power exercises a 

 restraining influence upon fermentation due to bacteria, and 

 1 Cowie, Journal Experimental Medicine, Vol. V., p. 205. 



