542 Phylum Mollusca 



adult. In the case of the oyster this developmental change is initiated 

 by an infinitesimal amount of copper (Prytherch, 1934) and may easily 

 be induced by placing a small piece of metallic copper 0.5 cm. square in 

 a 10 cc. solution of seawater for an interval of 15 to 30 seconds. Other 

 allied species, Mytilus, Mya, and Teredo, react similarly to this metal 

 and it may also be effective for stimulating setting of other marine 

 members of this class. Since under natural conditions many of these 

 species are concentrated at low water tidal levels it is probable that they 

 may be induced to set in aquaria by using water collected at this stage 

 of tide as has been done successfully with Ostrea. River water may 

 also be added to stimulate this reaction provided the quantity used 

 does not reduce the salinity to less than 10 per mille. 



Various devices may be employed for collection of spat, such as slides, 

 plates and tubes of glass, porcelain, wood, etc., on which the sedentary 

 species may be grown to the adult stage. Clean shells and cement coated 

 objects are practical for collecting spat stages of Ostrea and Anomia in 

 aquaria or may be used effectively under natural conditions according 

 to the methods described by Prytherch (1930) and Galtsoff, Prytherch, 

 and McMillin (1930). Many of the larvae will attach to the sides and 

 bottom of the aquaria and those having a byssus (Mytilus, Pecten, Mya, 

 and Venus) may be detached from the glass with a thin, sharp blade and 

 transferred to slides or shallow dishes for observation and to facilitate 

 handling until they grow to a convenient size. The post larval stages 

 should be kept in running water that has been strained through bolting 

 silk (No. 14 to 20) or monel metal wire cloth (100 to 200 mesh) until 

 they reach a size of 5 to 10 mm. Rapid growth may be obtained from 

 this point on by rearing them in trays or boxes, covered with galvanized 

 window screen, which are placed out of doors or in large tanks where 

 there is ample exchange and circulation of water. 



Bibliography 



Galtsoff, P. S., Prytherch, H. F., and McMillin, H. C. 1930. An experimental 



study in production and collection of seed oysters. V. S. Bur. Fish. Doc. 1088, 



Bull. 46:197-263. 

 Prytherch, Herbert F. 1924. Experiments in the artificial propagation of oysters. 



U. S. Bur. Fish. Doc. 961 -.4. 

 1930. Improved methods for the collection of seed oysters. U. S. Bur. Fish. 



Doc. 1076:47-59. 



1934. The role of copper in the setting, metamorphosis and distribution of 



the American oyster, Ostrea virginica. Ecol. Monog., Vol. 4, No. 1:47-107. 



Stafford, J. 1909. On the recognition of bivalve larvae in plankton collections. 

 Contrib. Canad. Biol. Rept. 14:221-242. 



1913- The Canadian oyster. Its development, environment, and culture. 



Commission of Conservation, Canada, Ottawa. 



Wells, William F. 1926. A new chapter in shellfish culture. Report, Conserva- 

 tion Commission, State of New York, 1925 (1926): 93-126. 



