The organisms are carried to the lymph nodes, which, acting as filters, retain them and for a time prevent a further extension.

The following illustrates the importance of the part the nodes may play in mechanically holding back a flood of infection.

A physician examined after death the body of a person who died from infection with a very virulent micrococcus and in the course of the examination slightly scratched a finger.

One of the organs of the body was removed, sent to a laboratory and received by a laboratory worker, a woman physician, who had slight abrasions and fissures in the skin of the hands from contact with irritating chemicals.

In the course of a few hours the wound on the finger of the man became inflamed, intensely painful, and red lines extended up the arm in the course of the lymphatic vessels, showing that the organisms were in the lymphatics and causing inflammation in their course.