PHYSIOLOGY: J. F. McCLENDON 
715 
^ Paris, C. R., Acad. Sci., 163, 1914, (428). 
" Ann. Physik., Leipzig, 29, 1909, (833). 
" Astroph. /., Chicago, III, 39, 1914, (189). 
THE EFFECT OF OXYGEN TENSION ON THE METABOLISM 
OF CASSIOPEA 
By J. F. McCIendon 
DEPARTMENT OF PHYSIOLOGY. UNIVERSITY OF MINNESOTA AND TORTUGAS LABORATORY, 
CARNEGIE INSTITUTION OF WASHINGTON 
Communicated by A. G. Mayer, September 21, 1917 
It was shown by Verzar (/. Physiol., 45, 1912, 39) that decreased 
oxygen tension in the blood capillaries decreased the metaboHsm of 
muscle but not of saHvary glands. The animal died before the oxygen 
tension in the salivary glands was reduced sufificiently to cause a notice- 
able fall in metabolism. In order to avoid complications in circulation, 
as in Verzar's experiments, I used the umbrella of Cassiopea in such a 
manner as to maintain a thin layer of cells of uniform activity constantly 
bathed with sea water at 30°. It had been determined in preliminary 
experiments that a rise of 10° in temperature doubled the metabolism, 
but that the hydrogen ion concentration could be changed within cer- 
tain limits without changing the metabolism to a degree that could be 
measured with certainty. The average of a large number of determi- 
nations placed the respiratory quotient at 0.95, but whether it was con- 
stant could not be determined. From the heat produced and nitrogen 
lost it was concluded that proteins with a small admixture of carbo- 
hydrates and fats were burned. 
Since the temperature was constant, the oxygen- tension was pro- 
portional to the 02-concentration, as determined by the Winkler method, 
the mean of the values at the beginning and end of the experiment being 
used. The metabolism was measured by the oxygen used, as that was 
determined more accurately than the heat and CO2 eliminated. The 
metabolism varied with oxygen concentration. This may be true of the 
cells of all animals. It seems possible that Verzar did not succeed in 
markedly changing the O2- tension in the salivary gland, owing to the 
great store of oxygen in the hemoglobin. There is, however, a distinc- 
tion between the metabolism of vertebrate muscle cells and Cassiopea. 
If vertebrates are' asphyxiated, the muscles give out lactic acid. A 
Cassiopea may remain without oxygen for seven hours without giving 
out CO2 or any other acid causing a noticeable change in hydrogen ion 
concentration, although in the presence of O2 such a change appears in 
