PHYSIOLOGY: A. G. MAYER 
627 
We know, indeed, from the studies of M. Henze that sea anemones 
use less oxygen the less its concentration in the sea water, and in 1917, 
J. F. McClendon found that the medusa Cassiopea can survive without 
apparent injury for more than seven hours in the absence of oxygen, 
and during this time does not give out CO2. Thus these coelenterates 
can temporarily suspend their metabolism for a protracted period if 
oxygen be absent. 
Winterstein's theory that death from heat is due to asphyxiation 
appears to be refuted by these experiments. 
E. N. Harvey, 1911, found that if the sea water be heated the rate 
of nerve conduction in Cassiopea augments in a right line ratio up to a 
certain point and then rapidly decHnes just before death ensues. 
In 1917, I found that this temperature curve, up to its maximum 
point, has no time factor. That is to say, the rate at 35°C. is the same 
whether the medusa be placed at once in 35°C. or warmed slowly for 
several hours until it arrives at this temperature. Moreover, the 
normal rate for 29° is regained almost immediately when the medusa is 
replaced in this normal temperature. 
When the rate is declining, due to injuriously high temperature, how- 
ever, I find that a time factor is involved, the decline becoming more 
pronounced as the heat is continued. Also, if after this the medusa is 
replaced in sea water of 29°C., its former rate is much reduced and 
may never be recovered, although if exposure to the heat was not 
too long or the heat not too excessive, a slow recovery is usually ob- 
served so that after a few hours the rate may again become normal. 
It will be recalled that Harvey, 1911, advanced the theory that some 
enzyme might be destroyed by the excessive heat, and being essential 
to nerve conduction, its loss caused the rate to decline. 
Our experiments however make it seem more probable that some toxic 
acid substance, possibly lactic acid or H2CO3, is formed under the influ- 
ence of excessive heat. It is easy to see how an acid of this sort might 
be eliminated and the rate gradually restored when the animal is re- 
placed in normal sea water, whereas if an enzyme were destroyed it 
might not so readily be replaced. 
In any event one or the other of the above mentioned hypotheses 
seems more in accord with the facts than does Winterstein's asphyxia- 
tion theory or the theory that death from heat is due to coagulation of 
proteid substances. 
Death occurs at too low a temperature for coagulation in most if not 
all proteids; and when killed, the animals are fully relaxed as shown by 
Harvey. Moreover, coagulated proteins could not readily be eliminated 
when the animal was restored to water at normal temperature. 
