178 Chiles WF. FLargitt 
As a modification of the experiment an attempt was made to 
displace the free oxygen by carbon dioxide. This was done in 
the usual manner by one of the assistants of the chemical labo- 
ratory. After boiling to drive off the free oxygen, the water was 
cooled and then charged with CO, from the generator and the 
flask closely stoppered. When an appropriate temperature had 
been obtained the same specimens were immersed in the carbon- 
ated water. For some time the specimens remained within the 
tubes. In two minutes one specimen protruded, but after some 
ten seconds retracted into the tube. In five minutes the other 
specimen did likewise, expanded the gills freely for ten seconds, 
then suddenly withdrew. ‘This process was several times repeated 
by both specimens. Later they expanded very slowly, and when 
fully out the shadow test was applied but without the slightest 
effect. ‘This test was repeated several times and with exactly 
the same negative effect. After about half an hour the specimens 
had apparently become sluggish and showed signs of discomfort. 
By means of a glass rod which had been thrust through the stopper 
they were gently touched, but gave no response. ‘This was vari- 
ously repeated with the same results. Finally they were removed 
from the flask and placed in a dish of normal water, one specimen 
remaining protruded during the transfer. 
In from fifteen to twenty minutes the specimens began to show 
signs of recovery, first to tactile stimulation, and inside of thirty 
minutes were also so far restored to normal activity as to react 
to the shadow test. 
As in the former experiment with oxygen reduction these were 
repeated the following day and with essentially the same results. 
It would seem as if the immersion in the carbonated water had 
acted to induce anesthesia, rendering the creature insensible to 
conditions. In no case was any injury perceptible, the specimens 
always recovering more or less readily when transferred to normal 
water. ‘This in some cases took place after a prolonged immer- 
sion of more than an hour in the carbonated water. 
This series of experiments were designed in the simplest way 
to afford some qualitative indication of the possible influences of 
a few of the most common and usual physical and chemical fac- 
