334 



W. J. CROZIER 



VI. RELATION OF PULSATION TO OXYGEN AND METABOLIC 



PRODUCTS 



a) Oxygen. It has previously been shown that holothurians 

 would live for relatively long periods in sealed jars of boiled sea 

 water (Crozier '15). This was in conformity with the observa- 

 tions of Moore and his colaborators ('12, '14), showing the small 

 amounts of dissolved oxygen used up in the activity of some 

 marine animals, including echinoderms. The isolated cloacal 

 ends of Stichopus continued to pulsate for over 700 minutes in 

 jars of sea water which had been boiled, sealed and subsequently 

 cooled to room temperature out of contact with the air. In pre- 

 paring this water the evaporation was very slight, but possibly 

 some faint increase in alkalinity was induced. The course of a 

 typical experiment is illustrated in figure 27 (B), plotted from 

 the record of experiment 78.3, with which may be compared the 

 control (A), begun at the same time. 



Experiment 78. S. July 10-11. Stichopus moebii, 20 cms. long; 60 

 seconds for 10 pulsations at 23.5°; volume of boiled sea water, 550 cc. 



The dependence of pulsation upon oxidations is probably indi- 

 cated, however, by the high toxicity of KCN, as, for example, in 



