C, N, or suspended matter in the surrounding water. All 4 tubule types were 

 present in each quahog sampled, showing that some intracellular digestion 

 occurred continually. Similar tubule types were clustered within the gland, 

 but a high degree of overall variability of tubule types was evident. Proper 

 tubule grading and analysis methods are therefore necessary in all studies 

 dealing with the changing morphology of bivalve digestive gland tubules. 

 - J.L.M. 



2194 



Robinson, W. E.,and R. W. Langton. 1980. 



Digestion in a subtidal population of Mercenaria mercenaria (Bivalvia) . 

 Mar. Biol. 58: 173-179. 



Hourly sampling of 4 to 5 quahogs was conducted over a 25 hr period in 

 August 1978 at Woods Hole, Mass. Crystalline style length did not vary sig- 

 nificantly with time, tide, particulate C, N, or suspended material in the 

 water. Changes in secretory activity of the style sac epithelium were not 

 evident from histological sections. Cellular morphological differences 

 allowed digestive tubules to be classified into one of 4 categories, indic- 

 ative of state of intracellular digestion within digestive cells. All 4 

 tubule types were present in each sample hr, signifying that intracellular 

 digestion occurs continually within the digestive gland. A 3 hr time lag is 

 evident between times of peak C, N, or suspended materials and apparent peak 

 levels of absorptive (Type II) tubules. - J.L.M. 



2195 



Rosser, Robin W. , John L. Schrag, Norio Nemoto, John D. Ferry, and Marion 

 Greaser. 1979. 



Infinite-dilution viscoelastic properties of two partially flexible macro- 

 molecules. J. Rheol. 23(1): 83-84 (abstract A2) . 



Paramyosin is a rodlike protein extracted from adductor muscle of Mercenaria 

 mercenaria. Two solvents were used, of widely different viscosities. Re- 

 sults were matched well by an empirical hybrid relaxation spectrum consisting 

 of one slow loss mechanism, corresponding to end-over-end rotation, together 

 with a series of faster loss processes; the relaxation times of the latter 

 were spaced as in the Zimm theory for the bead-spring model. - J.L.M. 



2196 



Ryther, J. H., and R. Mann. 1977. 



Bivalve mollusk culture in a waste recycling aquaculture system. Rept. 77- 

 59. Dept. Commerce, NOAA, Woods Hole Oceanogr. Inst., Woods Hole, Mass. 



Important references to Mercenaria mercenaria unlikely. Did not search 

 beyond SUNY-Stony Brook library. - J.L.M. 



2197 



Ryther, John, Thomas M. Losordo, A. Keith Furr, Thomas F. Parkinson, Walter H. 

 Gutenman, Irene S. Pakkala,and Donald J. Lisk. 1979. 



Concentration of elements in marine organisms cultured in seawater flowing 

 through coal-fly ash. Bull. Environm. Contam. Toxicol. 23(1-2): 207-210. 



In terms of toxicity the elements of most concern would be arsenic and 

 selenium. These were moderately elevated in Mercenaria mercenaria over con- 

 trols. Arsenic in marine species is present in various organic combinations, 

 which in shrimp have been shown to be largely excreted when fed to rats, as 

 compared to inorganic arsenic which is stored. Selenium, although toxic, is 

 also essential and deficient in the diet of many animals and probably humans. 

 Considering the relatively small proportion of marine species in the typical 

 American diet and the relatively modest increase in selenium concentration 

 in the fly ash-exposed organisms, this would not appear to constitute a 

 hazard. - J.L.M. 



610 



