160 



are concerned with a phosphorylating process; the significance of this to 

 mineralization is not clear. - J.L.M. 



Bevelander, Gerrit, and Paul Benzer. 1948. 



Calcification in marine molluscs. Biol. Bull. 94(3): 176-183. 



Several species were used as experimental animals, including Venus mercenaria. 

 Aside from the comment that venus and Codokia were better suited to histo- 

 logical and histochemical studies than the other species because they lack 

 heavy pigmentation in mantle tissues; and some photos of sections of Venus 

 mantle showing general topography, elaboration of conchin, distribution of 

 mucus, and distribution of alkaline phosphatase, there is no other specific 

 reference to hard clam. Presumably the conclusions apply generally to this 

 species. Calcification of shell occurs by formation of an organic matrix 

 upon which minute granules of calcium phosphate are deposited. Crystal 

 growth occurs in seawater in presence of mantle epithelium and in contact 

 with it. The enzyme alkaline phosphatase appears to be concerned with 

 calcification. Modification of certain constituents of seawater produces 

 a shell partially or completely lacking in mineral content. - modified author's 

 summary - J.L.M. 



161 



Bevelander, Gerrit, and I. Krimsky. 1949. 



Calcification in marine molluscs. II. Some aspects of phosphate metabolism. 

 Bermuda Biol. Sta. Ann. Rept. 1949, 3 p. 



Mevcenavia (Venus) mercenar-ia is not mentioned. Several mollusk species 

 were placed in aquaria of normal seawater into which radiophosphate (P^2) 

 had been introduced. Later analyses showed phosphate present in liver, 

 kidney, gonads, and other tissues. It was concluded that phosphate is 

 readily obtained via the digestive tract, and that phosphate is quickly 

 seized upon and stored in parts of the organism where it can be used later 

 in metabolism. Heavy deposits of phosphate were observed on the visceral 

 surface of the mantle in those areas occupied by mucous glands. Phosphate 

 is not an integral part of the mineral component of mature shell, but organic 

 matrix contains considerable amounts. Alkaline phosphatase was extracted 

 from mantle tissues of several molluscan species. Phosphatase also could be 

 extracted from the innermost layer of conchin which lies adjacent to the 

 shell. It appears that this enzyme acts extracellularly . Phosphatase is in 

 some manner associated intimately with growth and metabolism of those 

 substances which take part in shell formation. In vitro, phosphatase in 

 mantle tissues is capable of hydrolysing mucus in this region. Phosphorylation 

 is apparently one of the first of a series of events in calcification of 

 mollusk shell. - J.L.M. 



162 



Bevelander, G., and H. Nakahara. 1969. 



An electron microscope study of the formation of the nacreous layer in the 

 shell of certain bivalve molluscs. Calcif. Tiss. Res. 3: 84-92. 



163 



Bidwell, Milton H. 1940. 



A review of bacteriological shellfish scoring, 

 vention Addresses, 9 p., not numbered. 



Natl. Shellf. Assn. 



Con- 



Coliform organisms seem to serve as a fair measure of pollution in seawaters. 

 Coliform scores reported as M.P.N, have in general the same relative signifi- 

 cance. The relative intensity of coliform in shellfish and seawater is in 

 increasing order of seawater, oysters, hard clams, and soft clams. Seasonal 

 variation fails to greatly affect hard clams. - J.L.M. 



47 



