hard clam. Wholesalers reported a 25 to 50% decrease in demand for shell- 

 and finfishes, restaurant sales on Long Island were off as much as 50%. 

 Wholesale prices for clams from unaffected areas were down about 2 5% at 

 Fulton Market in N.Y. City. These reports may have been exaggerated, but 

 the record showed that although clam landings in 1972 had been uniformly 

 higher than average, landings were down substantially in 1973, coincidentally 

 with the bloom farther north. Erroneous reports in the local press probably 

 were responsible for consumer resistance, although scientific surveys in 

 New York waters found no evidence of toxic dinof lagellates. Red tides are 

 reported occasionally in New York waters, but investigations have consistently 

 shown that the causative organisms are harmless. An informational system 

 developed by industry and State and federal agencies responded quickly, and 

 may have prevented more damaging responses. - J.L.M. 



930 



Jensen, David. 1958. 



Some observations on cardiac automatism in certain animals. J. Gen. Physiol. 

 42(2): 289-302. 



Spontaneously beating hearts of Venus mercenaria are extraordinarily sensitive 

 to inhibition by very low doses of acetylcholine (ACh) and it was of interest 

 to test ACh for excitatory activity on hypodynamic clam hearts. On 2 

 spontaneously hypodynamic Venus hearts ACh (l:10ll to 1:10^) was completely 

 ineffective in producing or stimulating a beat. Threshold for inhibition in 

 a fresh heart was about 1:1010. Cocaine and ergonovine maleate were markedly 

 stimulatory. It was considered most surprising that proguanil was able to 

 stimulate molluscan cardiac tissue, which indicates at least superficially 

 basic differences in organization of different tissues, for proguanil inhibits 

 mammalian heart tissue and is antagonistic with ACh in this respect. ACh was 

 only inhibitory on clam hearts, and stimulation by cocaine in presence of ACh 

 inhibition was in direct contrast to experiments on rat heart. It was 

 concluded tentatively that rhythmic activity of myogenic tissues does not 

 depend upon an acetylcholine-cholinesterase mechanism, but upon another 

 biochemical process which may act upon and within cell membranes themselves, 

 perhaps through changes in permeability and ionic transport. Gradual decrease 

 of rhythmic activity in an isolated heart is a type of heart failure. An 

 understanding of stimulatory and pacemaker effects has important medical 

 implications. Research on Venus is important because beat is myogenic and the 

 heart is extremely sensitive to ACh. - J.L.M. 



931 



Jensen, L. D., et al. 1974. 



Environmental responses to thermal discharges from the Indian River Station, 

 Indian River, Delaware. Cooling water studies for the Electric Power Re- 

 search Institute, Dept. Geogr. & Envir. Engin., The Johns Hopkins Univ., 

 Research Project RP-49, Rept. 12: 106-126. 



See Jones, Jensen, and Koss (1974) . - J.L.M. 



932 



Jodrey, Louise H. 1953. 



Studies on shell formation. III. Measurement of calcium deposition in shell 

 and calcium turnover in mantle tissue using the mantle-shell preparation and 

 Ca 45 . Biol. Bull. 104(3): 398-407. 



Studies were made on Crassostrea virginioa . Mevcenavia (Venus) mercenaria 

 is not mentioned. - J.L.M. 



259 



