The Growth of the Soft Clam 307 



the bottom, is best. As the oyster culturist chooses cer- 

 tain bottoms on which oysters grow rapidly, so the clam 

 culturist may sometimes advantageously plant seed from 

 one and a half to two inches long in a current even- 

 strong enough to disturb the bottom. Growth is often 

 very rapid in such localities, but small clams planted in 

 them would be washed out or smothered. The rate of 

 growth depends directly on the amount of food that 

 the clam obtains, but the amount of food does not al- 

 ways depend on swiftness of current. There must be 

 some movement of water, but in some localities there 

 are so many food organisms in it that growth is rapid 

 when currents are sluggish. Such points must be proved 

 by trial in each locality. 



The idea of obtaining seed clams from artificially fer- 

 'tilized eggs should be dismissed at the beginning. Arti- 

 ficial fertilization of oysters eggs is easily accomplished, 

 but no one has yet been able to make any practical use 

 of it. With the eggs of Mya it is very difficult, and no 

 one is likely ever to make a success of rearing the young 

 from the egg. Furthermore, it would seldom be of value 

 in either case to be able to do so, for the natural supply 

 is sufficient. 



The set will always vary as the oyster set does. In 

 any locality it will be heavy one year and light another. 

 On one flat it may be a failure, usually from a local ad- 

 verse condition like a cold rain when the water is full of 

 swimming embryos. Several days of low temperature 

 may cause it to be more widespread. There seems, 

 however, seldom to be a failure over much of the shore 

 at one time. If necessary, it should be possible to pur- 

 chase seed at no great distance from any point where a 

 failure occurs. 



