16 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
happens is that the cocci multiply with great rapidity and 
invade and poison the tissues. After about twenty-four hours 
the injured part becomes swollen, red and painful because 
inflammation has set in. The redness and swelling gradually 
increase, and in a day or two yellow matter or pus will appear in > 
the centre of the inflamed area. Soon the matter escapes or is 
let out by the surgeon, and the redness and swelling disappear. 
The inflammation has subsided for the cocci are dead. How 
has the body succeeded in winning a victory over the cocci ? 
The victory has been won mainly by the assistance of the blood. 
To understand how this takes place we must consider 
the structure of the blood. A single drop of human blood 
contains, first, about five million small round bodies, incapable 
of movement, which carry oxygen and are spoken of as red 
cells, for they give the blood its characteristic colour; and 
secondly, about ten thousand larger bodies, white cells which 
have the capacity of movement, also of absorbing and digesting 
bacteria—these white cells are somewhat similar to the amoebae 
found in stagnant water. The third constitutent is the fluid 
or blood plasma in which the red and white cells float. When 
the battle is joined, battalions of white cells aad the plasma 
attack the bacteria, the white cells march up to them, swallow 
them, digest them, and so kill them. These white cells are 
called Phagocytes, and they will swallow twenty or thirty 
microbes at one meal, stuff themselves till they in turn are 
destroyed by the poisonous bodies of the bacteria. The 
phagocyte is usually compelled by an irresistible attraction 
to attack the bacterium: it is a case of forcible feeding. 
One can imagine the poor little creature who has been obliged 
to swallow a fatal number of bacteria say, as it dies, “ you 
made me love and I did not want to do it.” Thousands of 
phagocytes perish in the fray, and their dead bodies form the 
chief constituents of yellow matter or pus which appears after 
the inflammation of the finger has lasted some time. 
