168 UTILIZATION OF MINUTE LIFE. 



attain many leagues in length and a considerable 

 thickness. Leuwenhoek counted upwards of three 

 thousand young oysters moving about in the liquid 

 confined in the interior of the valves of the parent 

 mollusc. These minute beings are provided with 

 shells in about twenty-four hours after the eggs 

 that produced them are hatched. 



M. Graillon says that the oyster feeds chiefly 

 upon a green animalcule, called Vibrio navicularis ; 

 but others assert that it lives also upon vegetable 

 substances, such as the mucilage of sea- weeds, etc. 



The liquid contained in oyster shells has a com- 

 position very different from that of sea- water ; it 

 contains a notable amount of albumen, besides nu- 

 merous animalculse and flocculent vegetable matter. 

 It has lately been analysed by Payen, who finds it 

 composed of 85*98 parts of water, 1'33 of organic 

 matter, and 2*85 of mineral salts and silica. Ether 

 has the property of coagulating and throwing down 

 the albumen contained in this liquid. 



Some varieties of oyster live attached to the 

 roots or branches of trees that are periodically 

 covered by the rising tide. At the mouths of rivers 

 in South America and other tropical countries, 

 groups of magnificent oysters are seen thus sus- 

 pended together with that curious bivalve, Perna 

 ephippiwm, and are rocked to and fro by the balmy 

 sea-breeze when the tide retires. These are called 



