186 1^0 f RCE^^ OF EN FJia Y IN ANAEROBIOSTS 



a typical carbohydrate metabolism under anaerobic con- 

 ditions, is probable, but has not yet been definitely es- 

 tablished. It is known from the work of Putter (1907 

 and 1908), Laf argue and Fayemendy (1932a) and Bra- 

 connier-Fayemendy (1933) that the carbon metabolism 

 of these worms increases in the absence of oxygen, as is 

 evidenced by the increased excretion of organic acids, and 

 it is also a well-established fact that glycogen is present 

 (Vieweger, 1923; Vialli, 1927). It should not be difficult 

 to ascertain experimentally whether there is some con- 

 nection between these two sets of observations. 



Concerning free-living worms other than those men- 

 tioned in Table 23, it is known that a considerable amount 

 of glycogen occurs in Sipunculus and many sessile poly- 

 chaetes (von Brand, 1927; Chaigne, 1934). It has also 

 been shown qualitatively that some rotatoria occurring 

 in the sapropelis habitat store this polysaccharide (Laut- 

 erborn, 1916). It would be especially interesting to test 

 whether this is true also of the non-parasitic nematodes 

 of anaerobic habitats, since in their parasitic relatives the 

 carbohydrate metabolism is so markedly developed. 



Echinoderms. Small amounts of glycogen have 

 been found in Holothuria tuhulosa (Chaigne, 1934), and 

 in the muscles of Holothuria nigra. In the latter case it 

 has been shown that glycogen is transformed into lactic 

 acid during periods of activity (Boyland, 1928). An an- 

 nual cycle in glycogen content has been demonstrated in 

 Paracentrotus lividus and Asterias ruhens, varying quan- 

 tities of the polysaccharide being deposited in the pyloric 

 caeca and in the genital organs of these echinoderms. The 

 maximum is reached when the genital organs are fully de- 

 veloped (Chaigne, 1933a; cf. also Moore, "Whitley and 

 Adams, 1913 ; Kilborn and Macleod, 1920). Only traces of 

 glycogen, however, have been reported in the unfertil- 

 ized eggs of Arhacia punctulata (Perlzweig and Barron, 

 1928). 



