TRAN8ITI0X TO AyAEROBIOSTS 139 



1. INFLUENCE OF LOWERED OXYGEN TENSION ON OXYGEN 

 CONSUMPTION 



The invertebrates are usually divided into two groups 

 according to the degree of dependence of their oxygen 

 consumption on the oxygen tension. In the first group, 

 the consumption remains constant over a wide range of 

 tensions {cf. Table 17 and Fig. 9), while in the second 

 group, when the tension is gradually lowered, the con- 

 sumption soon drops, and in some cases it begins to drop 

 while the tension is still far above the highest met with 

 in nature [cf. Tables 18 and 19). 



To the first group belong the following representatives 

 of the various phyla: Peotozoa: almost all (Bledowski 

 and Zweibaum, 1915; Lund, 1918; Amberson, 1928; 

 Adolph, 1928; Baker and Baumberger, 1941); Coelen- 

 TEKATEs: Pelmatohydra (Palmhert, 1933) and several 

 jellyfish (Henze, 1910) ; Worms: planarians (Lund, 1921; 

 Hyman, 1929; Buchanan, 1931); Tuhifex (Harnisch, 

 1935a), Branchiura (Kawaguti, 1936), Hinido (Linde- 

 man, 1932), the larvae of Trichinella (Stannard, McCoy 

 and Latchford, 1938), perhaps Nereis (Hyman, 1932) 

 and the earthworm ( Konopacki, 1907 ; Dolk and van der 

 Paauw, 1929; Thomas, 1935; Kriiger, 1940; Kriiger and 

 Becker, 1940) ; Echixodeems: the eggs of various forms, 

 (Henze, 1910; Tang, 1931; Tang and Gerard, 1932) and 

 the holothurian Thy one (Hiestand, 1940); Molluscs: 

 some marine snails and some fresh-water and marine 

 lamellibranchs (Henze, 1910; Moore, Edie, Whitley and 

 Dakin, 1912; Dakin and Catherine, 1925; Eaffy, 1933; 

 Thamdrup, 1935), as well as the cephalopods (Henze, 

 1910 ; Amberson, Mayerson and Scott, 1925) ; Aetheopods : 

 many crustaceans (Henze, 1910; Marshall, NichoUs and 

 Orr, 1935 ; HeM, 1928 ; Kalmus, 1930 ; Maloeuf, 1937 ; Wey- 

 mouth, Crimson, Hall, Belding and Field, 1944), the de- 

 velopmental stages and adults of insects (Gaarder, 1918; 

 von Buddenbrock and von Rohr, 1922; Hiestand, 1931; 



