116 BACTERIOLOGY. 
with the number remaining. Occasionally the casting 
off of the bacteria allows them to infect 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 to Kruse, by (1) passive entrance through the 
stomata of the capillary walls; (2) carriage into the 
blood in the bodies of leucucytes; (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 
