166 MARVELS OF THE ANIMAL WORLD 



position of various stones, and that known as 

 rotten-stone or Tripoli^ — ^the latter term arising 

 from the fact that it was originally procTired from 

 the country of that name — is a red powder which 

 is used for giving a high polish to glass, marble, 

 metals, etc. ; while a stone called coral-rag is found 

 in Oxfordshire which owes its formation to coral- 

 polyps. The fine white powder obtained on the 

 shores of a lake in Sweden, and known as mountain- 

 meal by the natives who, in times of scarcity, used 

 to mix it with other ingredients when making 

 bread because of its supposed nutritive value, is 

 yet another substance which has its origin in animal 

 life. It consists entirely of the shell coverings of 

 minute animalcules. 



The remains of microscopic creatures are to be 

 traced also in opals, agates, and many flints. 



Many animal products were employed in the past 

 to cure various maladies, and we read that red 

 coral was considered by the Romans to have 

 medicinal properties, and was used by them in 

 the form of a necklace to hang around the necks of 

 their infants in order to preserve their teeth and to 

 assure that they became firmly fixed in the gums. 

 In Europe, finely -powdered cowry shells formerly 

 served as a remedial application for sores. The 

 gall of bears is used medicinally in China, as well 

 as a gelatine prepared from the skins of asses ; and 

 the Arabian doctors are stated to make use of a 

 preparation from the skunk as a remedy for elephan- 

 tiasis, leprosy, and other skin diseases. Even at 

 the present day the medical fraternity are indebted to 



