78 THE BODY AT WORK 



probably judicious to leave the problem at the frontier. Across 

 the frontier lies a fascinating land, rich with unimaginable 

 possibilities for the human race. Settlement is rapidly pro- 

 ceeding in this country, which is charted, like other border- 

 lands, with barbarous names : " antibodies," " haptors," 

 " amboceptors," " toxins," " antitoxins," and the like 

 finger-posts to hypotheses which show every sign of hasty and 

 provisional construction. But certain facts stand out, in 

 whatever way theory may, in the future, link them up. The 

 virus of hydrophobia, modified by passing through a rabbit, 

 develops in human beings, even when injected after they have 

 been infected, the power of resisting hydrophobia. The serum 

 of a horse which has acquired immunity to diphtheria aids the 

 blood of a child, which has not had time to become immune, 

 in destroying the germs of this disease. It is a contest between 

 the blood and offensive bodies of all kinds which find en- 

 trance to it. whether living germs or poisons in solution ; with 

 victory always, in the long-run, on the side of the blood, pro- 

 vided its owner does not die in the meantime. And not only 

 is the blood victorious in the struggle with any given invader, 

 but having repulsed him, it retains for a long while a 

 property which neutralizes all further attempts at aggression 

 on his part. In the past, physicians have fought disease with 

 such clumsy weapons as mercury, arsenic, and quinine. Now 

 they anticipate disease. In mimic warfare with an attenuated 

 virus the blood is trained to combat. Smallpox which has 

 been passed through the body of a cow is suppressed by the 

 blood's native strength. The exercise develops skill to deal 

 with the most virulent germs of the same kind. In cases in 

 which physicians cannot anticipate disease in human beings, 

 they train the blood of animals to meet it ; and, keeping their 

 serum in stock, they can, when the critical moment arrives, 

 reinforce the fighting strength of the patient with this mer- 

 cenary aid. 



The Spleen. The spleen is placed on the left side of the 

 body, and rather towards the back. It rests between the 

 stomach and the inner surface of the eighth, ninth, tenth, and 

 eleventh ribs. It is quickly distinguished from other organs by 

 its brown-purple colour, a sombre hue to which it owed its 

 evil reputation with the humoralists. The liver's yellow bile 



