PART II. 



RELATION OF OXYGEN TENSION AND ACTIVITY OF THE NERVOUS 

 SYSTEM TO METABOLISM IN CASSIOPEA.* 



Henze (1910a) observed that sea-anemones use less oxygen when less 

 is present in the sea-water, but interpreted this as due to the time 

 required for diffusion into the animal. That is to say, he supposed that 

 all of the cells were not supplied with oxygen when there was little in 

 the sea-water. If oxygen was entirely absent in some of the cells, the 

 decreased oxidation may have been merely the expression of the lesser 

 number of cells taking part in the metabolism. Burrows showed that 

 tissue cells require a certain oxygen tension for growth. Verzar showed 

 that the cat's heart is slowed by reducing the oxygen, and Loeb and 

 Wasteneys found that the heart-beat of Fundulus embryos may be 

 slowed by reducing the oxygen. The growth of Fundulus may be sus- 

 pended by lack of oxygen and may be slowed by diminishing the oxygen. 

 Johansen and Krogh found that plaice-fish eggs develop slower when 

 the oxygen tension is reduced. 



The calorimeter consisted of either an 850 c.c. or a 900 c.c. Dewar 

 flask (thermos bottle) inclosed in an air-tight container, which was 

 immersed in water that was maintained at the same temperature as 

 the water in the flask, within 0.003°. The technical difficulties were 

 met as follows: Two Beckmann thermometers were adjusted and com- 

 pared over the range of temperatures of the experiments and fitted 

 with reading-lenses to estimate down to 0.001°. A large tank of sea- 

 water was brought to 30° (which was about the temperature of the air) 

 and its pH and O2 and CO2 content determined. A cassiopea was in- 

 troduced into some of this sea- water that was dipped out into a jar. 

 The thermos bottle, stopper, and thermometers were iimnersed in the 

 large tank until they reached the temperature of the water. The 

 cassiopea was transferred to the thermos bottle and a perforated cork 

 stopper was inserted, with the exclusion of air-bubbles. One Beckmann 

 thermometer was inserted through the perforation in the stopper and 

 the other suspended in the tank, near the middle of the thermos bottle. 

 A small hole, remaining in the stopper for exit of displaced water, 

 was closed with wax. The pulsations of the cassiopea stirred the water 

 inside the thermos bottle, and the water in the tank was mechanically 

 stirred and was kept at the same temperature as that inside the thermos 

 bottle by additions of small portions of warmer or colder water as 

 required. The light was excluded by the silvering and coverings 

 of the thermos bottle, but in some experiments in which a 900 c.c. glass 

 jar with ground-glass cover was used in place of the thermos bottle, 

 the light could be excluded by darkening the tank, so as to prevent 



♦The content of this section was published as a separate paper in Jour. Biol. Chem., 1917, 

 xxxn, 275. 



235 



