116 BACTERIOLOGY. 



with the number remaining. Occasionally the casting 

 off of the bacteria allows them to iufect other places, 

 as in some cases where laryngeal and intestinal tubercu- 

 losis follows pulmonary tuberculosis. We must bear in 

 mind, however, that infection in these regions may have 

 been produced through the lymph and blood channels. 



In nearly all cases of infection the products of bacte- 

 rial growth are absorbed into the blood, and along with 

 them a few bacteria also, even when they do not repro- 

 duce themselves in it. The greater the extent of the 

 infection and the more deep-seated it is the greater is 

 the amount of absorption. The bacteria enter the blood, 

 according toKruse, by (1) passive eutrance through the 

 stomata of the capillary walls; (2) carriage into the 

 blood in the bodies of leucocytes; (3) growth of the 

 bacteria through the walls of the vessels; (4) transmis- 

 sion of the bacteria through the lymph-glands placed 

 between the lymph and bloodvessels. 



When bacteria are abundant in the blood they become 

 fixed in the capillaries of one or all of the organs, espe- 

 cially of the liver, kidneys, spleen, and lungs, and then, 

 by means of the leucocytes, which penetrate the capil- 

 lary walls, or, directly, they pass into the tissues and 

 substance of the organs. They thus reach the lymph 

 channels and glands, or through the secretions gain 

 entrance into the gall-bladder, saliva, etc., or press 

 through the epithelium, as in the alveoli of the lungs; 

 more rarely they pass through the excretions into the 

 urine, as in typhoid fever, though some deny that this 

 can happen unless there is a previous inflammation of 

 the kidneys. The passage of bacteria through the 

 breast is important, from the fact that milk is so 

 largely used as food. Many observers have reported 



