ARTIFICIAL RHYTHM. 205 
Over the tissue I lowered an inverted beaker filled 
with the gas the effects of which I desired to 
ascertain, and by progressively forcing the rim of 
the beaker into the water I could submit the tissue 
to various pressures of the atmosphere of the gas 
I was using. By an appropriate arrangement the 
electrodes passed into the interior of the beaker, 
and could then be manipulated from the outside, so 
as to be properly adjusted on the tissue. In this 
way I was able to observe that different gases 
exerted a marked influence on the rate of the 
artificial rhythm. 
The following table gives the ratios in the case 
of one experiment :— 
Rate of artificial rhythm, 
in air. In oxygen. In carbonic acid. 
36 per minute. 50 per minute. 25 per minute. 
It may here be observed that to produce these 
results, both carbonic acid and oxygen must be 
considerably diluted with air, for otherwise they 
have the effect of instantaneously inhibiting all 
response, even to the strongest stimulation. When 
this is the case, however, irritability returns very 
soon after the tissue is again exposed to air or to 
ordinary sea-water. But I desire it to be under- 
stood that the results of my experiments on the 
influence of oxygen, both on the natural and on the 
artificial rhythm, have proved singularly equivocal ; 
so that as far as this gas is concerned further 
observations are required before the above results 
can be accepted as certain. 
I have still one other observation of a very 
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