154 PRINCIPLES OF BACTERIOLOGY 



the gland could not be demonstrated. The finding of streptococci and 

 staphylococci is due probably in the majority of cases to the infec- 

 tions taking place as the milk is voided, for the epithelium at the outlet 

 of the lacteal ducts is always infected with staphylococci, and usually 

 streptococci, which have often been received from the mouth of the 

 sucking infant. 



Elimination of Bacteria by the Skin and Mucous Membranes. Whether 

 bacteria pass from the blood by the sweat is a mooted point. The 

 skin is always the seat of the staphylococcus and frequently of other 

 bacteria, so that it is difficult to determine in any given case the 

 origin of the bacteria found in the sweat. Many observers have 

 reported the passage of bacteria from the blood through the mucous 

 membrane. So long as the organs of secretion are not injured it is not 

 likely that many micro-organisms are eliminated from the blood in 

 this way. Bacteria are sometimes eliminated through the urine, but 

 here, as a rule, when great numbers of organisms are found, it is due to 

 development in the bladder. Such removal, moreover, has little if any 

 beneficial effect; but, on the other hand, it may be a source of danger 

 to others, as in typhoid fever. The removal of the poisonous products 

 of bacteria by the kindeys, intestines, etc., on the contrary, is of great 

 advantage to the organism. 



