46 BACTERIOLOGY 



upon the relatively large. It behoves the relatively large there- 

 fore, and man amongst their ranks, to keep their defences in 

 the highest state of efficiency. Just as a nation which becomes 

 opulemt and lazy, and refuses or forgets to keep its constituent 

 units in training and its defensive resources ever in readiness 

 even though it may appear to live for a time in safety is 

 surely and inevitably attacked and overcome by a foreign foe ; 

 so is the body of the individual, whose tissues and cells have not 

 learned to fight the invisible but ever-present foes around him, 

 certain to be attacked sooner or later. A man is " ill," not 

 merely when and after the visible symptoms of his disease are 

 upon him that is only when his fight against his enemies has 

 become more acute but he is already ill, and perhaps seriously 

 and critically ill, during the incubation or latent period of his 

 disease, when the invader has already entered his territory un- 

 known to him and is spying out his weak places. His outlying 

 fortifications, his skin or his mucous membranes, have already 

 been stormed. He must then, if health is to be preserved or 

 restored, have at his disposal an efficient regular mobile army, 

 the leucocytes of his blood both large and small, ready to rush 

 to the point of attack. His Territorials too, the local cells of 

 Ms tissues, must be ready to take their part in the fight. His 

 roads and railways are his blood and lymph-vessels, the lines 

 of communication which carry his fighting forces. His training 

 schools and recruiting stations are in the marrow within his 

 bones (where most of his active fighting blood-cells are pro- 

 duced) as well as in other tissues his spleen and his lymphatic 

 and other glands, where fighting cells are also present which 

 may seize upon and destroy any of the invaders which reach 

 them. The weapons too must be ready not only of defence 

 but of offence his bullets and his bayonets are his various 

 ferments and antibodies, such as antitoxins to neutralise the 

 poisonous toxins of the invading bacteria : antibacterial or 

 bactericidal ferments to attack the bodies of his foe, aggluti- 

 nins to paralyse them, bacteriolysins to dissolve and disinte- 

 grate them, and a thousand other subtle and as yet little-known 

 substances with which the wonderful nation of his body-cells 

 is equipped for the fray. This is not all mere journalistic 

 imagery, but stern reality, and in this battle no quarter is given 

 on either side. Even amongst his own troops, no mercy is 

 shown to the weak or to the severely wounded. Leucocytes 

 which have done their duty and have suffered in the process and 

 are beyond recovery, are simply eaten by their larger brethren 

 on the spot, or in some of the organs to which they are carried, 

 or they are discharged altogether from the body along with 

 bacteria and broken-down tissues in the form of pus. 



