585 



Flemer, David A., William L. Dovel, Hayes T. Pf itzenmeyer, and Douglas E. 

 Ritchie, Jr. 1968. 



Biological effects of spoil disposal in Chesapeake Bay. J. San. Eng. Div. 

 94(SA4) Proc. Am. Soc . Civil Eng., Paper 6081, Aug .: 683-706 . 



Natural populations of most benthic species are at their lowest levels of 

 abundance in Nov and Dec, just before recruitment of juveniles. Late fall 

 appears to be the season when dredging would have least effects. Mereenaria 

 mereenaria is not mentioned. - J.L.M. & M.W.S. 



586 



Florey, Ernst. 1967. 



The clam-heart bioassay for acetylcholine. Comp. Biochem. Physiol. 20(2): 

 365-377. 



The clam-heart bioassay is sensitive, specific, and convenient. Accuracy 

 of better than -10% can be obtained by matching reduction in amplitude of 

 ventricular beat produced by known concentrations of acetylcholine (ACh) 

 and by tissue extracts. Isolated ventricle is mounted in a bath of known 

 volume and contractions are recorded on a kymograph or by a mechanoelectric 

 transducer on a chart recorder. ACh standards are made up in buffered 

 saline of pH 6.5. The following steps are taken: 1) establish range of 

 sensitivity of test ventricle; 2) establish range of effects of applying 

 ACh concentrations in 10 steps of 20% difference, covering a 10-fold 

 increase in concentration; 3) bioassay proper in which known and unknown 

 ACh concentrations are matched. Pharmacological (blocking agents) , 

 enzymatic (cholinesterase) and chromatographic procedures are used to 

 detect interfering substances in tissue extracts and to establish that 

 detected activity is indeed caused by ACh. Methods of calculating data 

 and determining degree of accuracy of individual determinations are 

 illustrated by examples. Relative molar quantities of various cholinesters 

 that cause inhibition of Mereenaria ventricle equivalent to that produced 

 by a molar quantity of ACh equal to 1 are: carbamylcholine 80, propionyl- 

 choline 105, butyrylcholine 62 5, acetyl-6-methylcholine 1,100, choline 

 14,000, and benzoylcholine 15,000. ACh was by far the most active of 16 

 related compounds. - J.L.M. 



587 



Florey, Ernst, and M. A. Cahill. 1977. 



Hemodynamics in lamellibranch molluscs: Confirmation of constant-volume 

 mechanism of auricular and ventricular filling. Remarks on the heart as 

 site of ultrafiltration. Comp. Biochem. Physiol. 57 (1A) : 47-52. 



Mereenaria mereenaria and M. eampeehiensis are mentioned only in reference 

 to the work of Tiffany (1972) abstracted elsewhere in this bibliography. 

 - M.W.S. and J.L.M. 



5 J 



Florey, Ernst, and Harriet J. Merwin. 1961. 



Inhibition in molluscah hearts and the role of acetylcholine. . In Nervous 

 Inhibition. Ernst Florey (edj . Pergamon Press, Oxford, England, p. 136-143. 



Among invertebrates only mollusks have a heart with morphological and 

 physiological properties comparable to that of vertebrates. The molluscan 

 heart is chambered, and blood enters atria through large veins and leaves 

 ventricle through 1 or 2 aortae. In most mollusks the heart receives a 

 double innervation of acceleratory and inhibitory nerve fibers. The great 

 sensitivity of several mollusk hearts (including Mereenaria mereenaria) to 

 acetylcholine (ACh) and the fact that ACh causes cardiac inhibition also 

 are similarities to vertebrate hearts. Textbooks say that heartbeat in 

 mollusks is myogenic, but a number of species have ganglion cells in walls 



164 



