520 



Dugal, Louis-Paul. 1939. 



The use of calcareous shell to buffer the product of anaerobic glycolysis 

 in Venus mercenaria. J. Cell. Comp. Physiol. 13(2): 235-251, ill. 



When hard clams are kept out of water, CO2 content of the mantle cavity 

 fluid increases from 8 vols. % to 150 vols. %, CO2 content of the central 

 inner part of the mantle increases, and shell is visibly eroded under the 

 central part of the mantle. If the clam is returned to seawater the C02 

 content of the mantle cavity fluid returns to normal. If removed from the 

 water again, the process is reversed. The increase in CO2 tension is small 

 compared to the increase in total CO2 . Ca of the fluid increased more than 

 CO2, which shows that another acid or acids are formed. There is no great 

 change in pH, which shows that the other acid is neutralized and buffered. 

 Glass electrode titrations showed that the pk of that acid corresponds with 

 the pk of lactic acid. This acid increases in concentration with total CO2 

 and Ca. The sum of CO2 and other acid is equivalent at any time to the Ca. 

 It was concluded that clams survive out of water through anaerobic 

 metabolism. A process like glycolysis forms an acid which is buffered by 

 CaC03 dissolved from the shell, and part of the CO2 coming from that CaC03 

 remains in solution. The CO2 gained by the fluid is derived from the shell 

 and is not produced by metabolism. Since the sum of CO2 plus non-volatile 

 weak acid is equivalent to Ca, these are the only participants in buffering. 

 Calcareous shell is used for buffering products of glycolysis. - from 

 author's summary - J.L.M. 



521 



Dugal, L.-P. and L. Irving. 1937. 



Secretion of CaCC>3 from the shell by closed Venus mercenaria. Can . J. Med. 

 36: 81. 



SUNY Library at Stony Brook could not locate this journal in any Union List. 

 They did find the Canadian Medical Assn. J. 36 (1937) but the article was not 

 on p. 81 nor was it listed in the volume index. Search terminated. - J.L.M. 



522 



Dugal, Louis-Paul, and Laurence Irving. 1937. 



Increase in CO2 and decalcification in certain pelecypods. Biol. Bull. 

 73(2): 379. 



Mantle cavity fluid of Venus mercenaria gains CO2 when the clam is held 

 out of water. In a fresh clam the change is from 5 or 8 ml to 90 ml/100 ml 

 of fluid in 5 to 6 days. When clams begin to die total CO2 decreases. 

 Return to water before death restores CO2 to normal. In Venus the total 

 CO2 of the fluid increases rapidly, but pH decreases only from 7.4 to 7.2 

 and Pco2 increases only from 3 to a max of 25 mm Hg, so it is evident that 

 buffering capacity increases. Shell is eroded during these changes. A few 

 analyses showed that the fluid gained Ca, which suggests that buffering is 

 provided by solution of CaC03 from shell. Shell erosion is localized in 

 the central inner part; only mantle tissue gains CO2. Thus, buffering is 

 effected by activity of a special tissue. - J.L.M. 



523 



Dugal, Louis-Paul, and Laurence Irving. 1937. 



Secretion de carbonate de calcium per les Venus mercenaria fermees 

 hermetiquement. Compt. Rend. Soc. Biol., T. 124(1): 526-528. 



When Venus mercenaria is taken from the water it closes its valves 

 hermetically and holds in its pallial cavity the water which it had taken 

 at that moment. CO2 content of this water is 5 to 8 cc/100 cc liquid. CO2 

 content increases rapidly up to 60 cc/100 cc liquid. V. mercenaria can 



145 



