concentrations, moderate necrosis and sloughing of ciliated epithelial 

 layers at higher concentrations. Blood sinuses were distended and contained 

 precipitated hemolymph. In gills, only chitinous supporting rods remained 

 at 50000 ppb phenol. Electron microscopy also showed damage to epithelial 

 cells. Cell and nuclear membranes remained intact at low concentrations; 

 intracellular organelles (lysosomes, mitochondria, etc) were in various 

 stages of disintegration. At 10000 ppb cell membranes ruptured. Hemocytes 

 showed extensive intracellular damage; at 1000 ppb and above only the hyaline 

 cells remained intact. - authors' abstract - J.L.M. 



614 



Frizzell, D. L. 1936. 



Preliminary reclassification of Veneracean pelecypods. Bull. Mus . Roy. 

 d'Hist. Nat. Belgique 12(34): 1-84. 



Proposed separation of Mercenaria from Venus as a distinct genus. - from 

 Wells, Ecology 38(1), 1957 - J.L.M. 



615 



Frontali, N., L. Williams, and J. H. Welsh. 1967. 



Heart excitatory and inhibitory substances in molluscan ganglia. Comp. 

 Biochem. Physiol. 22(3): 833-841. 



In several mollusks an antagonistic cardio-regulatory action of acetylcholine 

 (ACh) and 5-hydroxytryptamine (5-HT) has been demonstrated. Dopamine also 

 occurs in mollusk ganglia. An unidentified heart-excitatory factor, 

 presently called Substance X, also has been found. Eluted fractions were 

 assayed on isolated hearts of Mercenaria mercenaria treated with 1-methyl- 

 lysergic acid butanolamide and with Mytelase to counteract 5-HT and ACh. 

 Extracts from ganglia of M. mercenaria gave four peaks of cardio-excitatory 

 activity. Extracts from hard clam hearts gave only three. The first 3 peaks 

 were completely inactivated by proteolytic enzymes, but the 4th was not 

 inactivated. ACh, 5-HT, and dopamine have low molecular weights. Substance 

 X is considered to be a mixture of several compounds. - J.L.M. 



616 



Frost & Sullivan, Inc. 1974. 



Fish farming in the U.S.A. Frost & Sullivan, Inc., New York, N.Y. 

 Privately published by photo-offset from typescript, vi+199 p. 



Diminishing supplies of marine fishery products can be offset by 

 mariculture. The study projects present and future clam markets in the 

 U.S. as follows: 1973 - 0.4 lbs; 1976 - 4.0 lbs; 1979 - 6.0 lbs; 1982 - 

 9.2 lbs. (Abstracter's note: it is not clear whether these are per 

 capita markets or whether the legend to the table should have specified 

 millions of lbs. The figures are for clams produced by mariculture, not 

 total market amounts.) It was concluded that mariculture has great 

 potential for growth and profit. The report considers 5 groups of fish 

 and shellfish, and aquaculture and mariculture generally around the 

 world. Virtually all clams consumed in the U.S. are produced in domestic 

 waters. Quahog is the principal species. Techniques for spawning and 

 rearing larvae are well established. Wild clams are used as breeding 

 stock. Best results are obtained with a hybrid of northern and southern 

 quahog (Mercenaria mercenaria and M. campechiensis ) , which grow faster 

 and produce about twice the yield of parent strains. Spawning is 

 stimulated by temp shock, alternating water temp between 20 and 30°C at 

 30 min to 8 hr intervals. Eggs are released into a sperm suspension. 

 Extraneous materials are removed by sieving and placed in culture tanks 

 of filtered water. Water is replaced about 3 times/week. Larvae are 

 fed fresh algae. This is currently a limiting factor because only fresh 

 unprocessed algae can be used. If algae were available year-round, clam 

 production could be increased significantly. About 1,000 clams can be 

 reared to 5 mm in 4 1 of water. As soon as possible, young clams are 

 planted in seawater, usually at 500 clams/m^. Site selection is 



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