SOURCES OF ENERGY IX AXAEROBIOSIS 187 



Molluscs. A considerable accumulation of gly- 

 cogen is regularly encountered in lamellibrauchs (Bizio, 

 1866; Chittenden, 1875; Mitchell, 1915; McDowell, 1927; 

 Kobayashi, 1929 ; Okazaki and Kobayashi, 1929 ; Boyland, 

 1928; Semichon, 1932; Masumoto, Masumoto and Hi- 

 bino, 1934; Chaigne, 1934) and in gastropods (Hammar- 

 sten, 1885; Barfurth, 1885; Bellion, 1909; Schondorff, 

 1912; Boyland, 1928; Petree and Alsberg, 1929; von 

 Brand, 1931; May, 1934; Chaigne, 1934; Baldwin and 

 Bell, 1940) ; while cephalopods store only insignificant 

 amounts (Starkenstein and Henze, 1912; Boyland, 1928; 

 Chaigne, 1933). It should be remembered in this connec- 

 tion that only members of the two former groups tolerate 

 well the lack of oxygen. 



Berkeley (1921) is the only investigator who compared 

 the glycogen consumption of lamellibrauchs under aero- 

 bic and anaerobic conditions, but his results are rather 

 inconclusive. Saxidomus giganteus lost, during periods 

 of equal length in the absence and in the presence of air, 

 amounts of glycogen equal to 0.99 and 0.28 per cent of 

 the body weight resjDectively. The ratio of the two 

 figures, 3.5, approximates that found in free-living 

 worms. No similar difference in glycogen degradation 

 was encountered with Mya arenaria and Paphia sta- 

 minea. A survey of Berkeley's figures indicates, however, 

 that his material was probably not uniform. This is sug- 

 gested by the fact that at least in one series of experi- 

 ments the anaerobically starving animals had a higher 

 glycogen content than the controls analyzed at the be- 

 ginning of the experiment. 



Dugal reported recently (1940), in a preliminary note, 

 that an anaerobic metabolism can be demonstrated in 

 Venus mercenaria kept under anaerobic conditions as 

 long as the hepato-pancreas contains glycogen, but fur- 

 ther details on his experiments are needed for the evalua- 

 tion of the results. 



