SAND-HOPPERS I57 



gives it the luminosity of a glow-worm, inevitably and 

 rapidly causes its death — a severe price to pay for brief 

 nocturnal effulgence. Some of the germs can be re- 

 moved on a needle's point from the dead sand-hopper 

 and introduced by the most delicate puncture into a 

 healthy sand-hopper or into a young crab, with the 

 result that they too become illuminated, the bacillus 

 multiplying within them. Being thus morbidly il- 

 luminated and having astonished the crustacean, not to 

 say the human world, by their alarming brilliance, they 

 quickly perish : a little history which may be read as a 

 parable. The sand-hoppers give the disease to one 

 another. It is, of course, a merely non-significant thing 

 that the bacillus happens to set up light vibrations. 

 Its chemical activity is concerned with its nourish- 

 ment and growth, and in the course of these processes 

 it not only produces light but poisonous by-products 

 which kill its host. Some day we may get an 

 " immune " race of sand-hoppers who will acquire the 

 illuminating bacillus and defy its poison. Then we 

 shall have a permanent and happy breed of brilliant 

 sand-hoppers illuminating the dark places of the 

 seashore. 



It is conceivable that some of the disease-producing 

 bacilli (bacteria, cocci, etc.) which multiply in man's 

 blood and tissues should also produce light vibrations, 

 and if one could be found that would render the blood 

 luminous, whilst not producing much pain or malaise, 

 no doubt some excuse would be found for its use as 

 a fashionable toilet novelty. Cases are on record of 

 luminosity of the surface of the body and its secretions 

 being developed during serious illness by human beings, 

 especially in acute phthisis ; but these ancient records 

 need confirmation. 



