DOCTRINE OF A COXTAGIUM VIVUM. 35 



respiratory and digestive tubes, and will effectually prevent the 

 introduction of the germs to the lymph and blood channels if the 

 mucous membrane be healthy. We may look upon this line of 

 defence as by far the most important, both by its protective 

 influence, and by its destructive action on the germs through the 

 solvent action of the digestive juices. 



But now, supposing that the living bacilli, or their spores, 

 have passed this first barrier, they may then reach either lymph or 

 blood channels, and may, of course, give rise to general blood- 

 contamination, or may even then be destroyed by the defensive 

 action of the lymphatic glands or leucocytes. Here we have a 

 second and a third barrier, which may effect the destruction of 

 the germs before they have had time to germinate, and recent 

 observations show that the agency of lymphatic glands as vital 

 filters has not been fully realized. 



In the case of the chimpanzee, the disease introduced by the 

 food — possibly by means of milk — had affected an immense 

 number of the mesenteric glands. These had retained the bacilli, 

 which were present in the liquid pus resulting from the breaking- 

 down of the diseased glands. The pus and the contained bacilli 

 might then be discharged from the body if an outlet could be 

 found, or it might gradually dry up, leaving a harmless calcareous 

 mass. 



Dr. Sims Woodhead has recently directed attention to the 

 agency of the lymph-glands in arresting tuberculosis. He points 

 out the fact that commonly tuberculosis of glands is the primary 

 lesion, and that the glands in the root of the lungs may become 

 tuberculous in mesenteric cases, the tubercle in the lung itself 

 being of more recent growth. The connection between milk- 

 feeding and tuberculosis is clearly established, as showing that the 

 virus reaches the mesenteric glands by the alimentary canal. It 

 has been found that, although tubercular disease of the mamma is 

 in the human subject rare, yet it is common in cattle, and that 

 bacilli are always found in the milk in these cases. Recently, it 

 has also been found that tuberculous cows give contaminated milk, 

 even although the mammary glands may not be diseased. The 

 connection of infantile tuberculosis with milk is shown by the 

 following table of cases of mesenteric disease : — 



