THE OYSTER AND THE OYSTER INDUSTRY. 29 



ing of ground for this purpose and dependence is placed largely on 

 natural beds for the supply of oysters. 



In some few cases a State plants a limited amount of cultch upon 

 certain partially depleted natural beds for public benefit. In gen- 

 eral, however, the natural beds are staked off and reserved for general 

 public use by the ''natural growther" subject to certain restrictions, 

 mentioned elsewhere. 



The principal considerations involved m this method of oyster cul- 

 ture are character of the cultch, character and preparation of the 

 bottom, time for planting cultch, the proper location of cultch beds 

 with respect to tides and currents and the spawnmg oysters, and the 

 location of beds of spawning oysters. 



Cultcli. — ^ While formerly limited use was made in the United States 

 of various forms of cultch — such as tin cans, bits of pottery, brush, 

 pebbles, "jmgle" shells, and oyster shells — only the last three mate- 

 rials have proved to be of practical value, and at the present time the 

 cultch used consists almost entirely of oyster shells. A few "jingle" 

 shells are known to be employed at one point in Long Island Sound. 

 Oyster shells are large and afford surface for the attachment of quan- 

 tities of spat (PL IV). As this grows, overcroAvdmg is apt to result, 

 since the shells are too heavy to be broken apart by the pressure of 

 the developing set. This is overcome by breaking apart and culling 

 the clusters thus formed. 



The advantages of oyster shells as cultch consist largely in their 

 general adaptability, presentmg a smooth surface for the attachment 

 of the set, and theu' abundance and convenience, smce an oyster- 

 shucking house has only to turn about and convert its shell pile into 

 spat collectors by the use of its own boats. At the same time the 

 gradual dismtegration of the shells provides lime for the succeeding 

 generations. 



" Jmgle" shells, or silver shells, belongmg to the species of Anomia, 

 and scallop shells are thinner and more fragile than oyster shells. 

 Consequently, they make a superior form of cultch, smce the pressure 

 of the growmg yomig oysters breaks them apart and the formation of 

 clusters is prevented. Unfortunately, the supply of such shells is so 

 limited that very few are now used. 



Character and frefaration of hottom.- — If the bottom at the pomt 

 where it is desired to plant cultch is sufficiently hard to support it a 

 layer of shells is spread upon it broadcast, as previously described. 

 In case the bottom is soft, it may be prepared by putting down sand 

 or gravel in sufficient quantities to support the shells. Often, hov.'- 

 ever, the bottom is stiffened merely by the use of shells. Sufficient 

 quantities are put down and allowed to smk, until a substratum is 

 formed firm enough to support a layer of cultch several inches or a 

 foot thick above the ground. A bed on which cultch has been placed 

 for several years in succession will gradually be made firmer by the 

 setthig of a part of the shells. 



Time for planting cultch. — Since sea water always contains more or 

 less suspended debris, which gradually settles upon the bottom or any 

 object thereon it follows that cultch will more or less rapidly become 

 coated with a layer of slime or debris. If this becomes too thick the 

 oyster larvte are prevented from setting upon it. Movement of the 

 water by tides and currents obviates this difficulty somewhat by 

 washing the debris from the cultch. In bodies of water where there 



