Metaphor for the Spread of Disease

To choose a rough example, think of a thorn which has stuck in a finger and produces an inflammation and suppuration. Should the thorn be discharged with the pus, then the finger of another individual may be pricked with it, and the disease may be produced a second time. In this case it would not be the disease, not even its product, that would be transmitted by the thorn, but rather the stimulus which engendered it. Now supposing that the thorn is capable of multiplying in the sick body, or ...

 Death by Phosphorous Poisoning

The autopsy of a person who had died from phosphorus poisoning would reveal inflammation a haemorrhage in the stomach and bowel, the liver would show fatty changes and both it, and the kidneys would be enlarged, greasy and of a yellow colour. But the most convincing proof of death due to phosphorus exposure would be to turn off all the lights in the mortuary and see its tell-tale glow...