122 Our Food Mollusks 



cess ful results have been obtained from them. Though 

 a great many young may attach to a can, the corrosive 

 action of the salt water soon reduces it to fragments, 

 thus freeing the oysters before they have begun to crowd 

 each other and eventually the cultch is entirely de- 

 stroyed. 



It would be possible to manufacture saucer-shaped col- 

 lectors of thin sheet-steel, gypsum, cement, tar, or as- 

 phaltum, that would be successful where currents were 

 not rapid — the targets or " clay pigeons " used by trap- 

 shooters would be ideal for the purpose — but the cost, in 

 any case would be prohibitive, and it is not likely 

 that any form of cultch will be discovered or invented 

 that will take the place of the shell collector in our 

 waters. 



One of the things learned early in the practice of 

 oyster culture was that collectors may be placed on the 

 bottoms only after the breeding season has arrived. 

 Usually it will not do to plant the shells at any conven- 

 ient season during the year to await the appearance of 

 swimming embryos. The reason for this is that they 

 soon become covered by a slime upon which the young 

 oysters are unable to attach. The material which thus 

 coats all exposed parts of the shells is composed of ma- 

 rine algae, diatoms, hydroids, or sponges. These organ- 

 isms are apparently able at all seasons to establish them- 

 selves, and their growth is rapid. It is therefore neces- 

 sary to have the collectors ready on shore, and to spread 

 them on the collecting grounds after the oysters have 

 begun to spawn. Spat then attaches before the slime 

 coat has formed. 



If, during July, August, or September, the spat has 

 failed to attach on the collectors, it may be necessary to 



