Marvels of the Universe 



285 



It has been found that all species of pearl-bearing shells are 

 Some, indeed, owe their pearls to the desire to rid themselves of 



teeth. An imitation is easily detected by its hard, slippery surface, for the real gem always 

 feels gritty. 



Mention has already been made of the primary cause of pearl formation — the embedding of a 

 minute organism in the body of the mollusc. Researches have lately been caiTied out to ascertain 

 the exact nature of this organism, 

 not attacked by the same parasite, 

 the irritation caused by a minute 

 grain of sand or particle of wood. 

 A photograph is given on page 

 284 which shows a small fish that 

 has entered the shell of a mollusc 

 and has been entombed in nacre 

 by the oyster. But as the Ceylon 

 oyster fisheries produce the finest 

 pearls, the parasite of the Ceylon 

 oyster is most worthy of investi- 

 gation. It has been proved by- 

 Professor Herdman to be the grub 

 of a tapeworm. This grub be- 

 comes embedded in the oyster, 

 dies, and is entombed by its host 

 in fold on fold of nacre ; while 

 the form of the grub, which is 

 globular, influences the shape of 

 the pearl. 



So it is with a dead worm in 

 its little shining tomb that the 

 woman of fashion adorns herself. 

 It is the possession of numbers of 

 little dead worms hidden in lus- 

 trous globes that makes her to be 

 envied of her fellows. " Vanity of 

 vanities," saith the preacher, " all 

 is vanity ! " 



FALSE SCORPIONS 



Among the surprising adventures 

 of Sinbad the Sailor, it is related 

 that he once found himself sur- 

 rounded by precipitous chffs up 

 which it was impossible to climb. 

 After fruitless efforts, he at last 

 made his escape by tying himself 

 to the leg of a " roc," a gigantic 

 bird, which flew out of the 

 valley carrying Sinbad. Possibly 

 a somewhat similar service is 

 rendered by the house-fly to the 



Pholo *»] 



SucK 



[/■'rneaf }fnrrltige 

 A FALSE SCORPION. 



the name given to this formidable-looking creature, which, however, 



is here represented about forty-seven times larger than the natural size. With its 



great nippers it attaches itself to the leg of a fly. using its host as a means of 

 conveyance. 



