SURVEY OF INVERTEBRATES 61 



Corals can be kept alive for some time in water poor in 

 oxygen (Yonge, Yonge and NiehoUs, 1932). The most 

 resistant genus so far known is Pontes. Representatives 

 of this genus, in the experiments of the authors just men- 

 tioned, lived for 6 days when confined in a closed con- 

 tainer. The water in the container had an initial oxygen 

 content of 0.51 cc. per liter, while at the end of the expe- 

 riment it was completely free of molecular oxygen. 



The resistance of jellyfish to lack of oxygen varies ap- 

 parently with the genus, but is certainly not very pro- 

 nounced in any of them. Rhizostoma seems to become 

 asphyxiated quite rapidly (Winterstein, 1905; Baglioni, 

 1905), whereas Cassiopea xamacJiana could be kept for 

 7 hours (McClendon, 1917), and Eleutheria dichotoma for 

 12 hours (Drzewina and Bohn, 1911) under anaerobic 

 conditions. In this last case, curious developmental 

 changes were observed. While normally young daughter 

 medusae originate from buds formed in the angles be- 

 tween the tentacles, under the influence of a lack of oxy- 

 gen supernumerary tentacles originated from the buds 

 and the formation of the daughter medusae was com- 

 pletely inhibited. 



Certain functions of the polyps of coelenterates are 

 much more dependent upon an adequate supply of oxy- 

 gen than is their general metabolism. According to Mil- 

 ler (1937), Barth (1938, 1940) and Schechter (1941) 

 oxygen appears to be the controlling factor in the re- 

 generation of the hydranths of Tubularia and Corymor- 

 pha. In the latter, a considerable inhibition became no- 

 ticeable even when the oxygen content of the water was 

 lowered only 20 per cent below the normal value. Under 

 nearly anaerobic conditions no regeneration whatever 

 took place. While these experiments seem to indicate 

 a close correlation between oxygen consumption and re- 

 generation, further information is desirable. Barth 

 (1940) writes in conclusion to the experiments reported: 

 "Thus the rate of regeneration and the rate of 0., con- 



