214 
Proceedings of the Royal Society 
common air was introduced into the chamber instead of ozonised 
air, or if the frog was taken out of the chamber, it quickly recovered. 
These effects may be seen in the following experiment : — 
A large healthy frog was introduced into the air-chamber, through 
which a current of air was passing sufficient to fill a litre flask 
in three minutes. At the end of two minutes, the respirations were 
96 per minute. The induction machine was then set to work, so as 
to mix ozone with the air, the current passing through the chamber 
at the same rate. In half a minute the eyes were affected, and the 
respirations were reduced to 8 per minute. At the end of six 
minutes, the animal was quite motionless, and the respiratory 
movements had entirely ceased. Pure air was then introduced. 
In half a minute, there was a slight respiratory movement, and in 
eight minutes, the respirations numbered 85 per minute. At the 
end of other twelve minutes, ozone was again turned on, with the 
same results. The animal in this experiment was then subjected 
to atmospheres of common air and air mixed with ozone alter- 
nately, each period of immersion in the atmosphere consisting of 
ten minutes, with invariably the same effect. At the end of two 
hours it was removed from the chamber, and recovered. 
In the case of the frog which died after being exposed to an 
atmosphere of ozonised air for an hour and a half, the heart was 
found pulsating after systemic death. It was full of dark-coloured 
blood. The lungs were slightly congested. In every part of the 
body the blood was in a venous condition. 
In two experiments, frogs were exposed to the action, not of air 
mixed with ozone, but to a stream of oxygen mixed with ozone, 
and the results were somewhat different from those just narrated. 
The effects were not so well marked. When a frog was introduced 
into an atmosphere of pure oxygen, the animal was lively and 
vivacious, the eyes were wide open, and the respiratory movements 
were greatly accelerated. But when the oxygen contained a con- 
siderable quantity of ozone, the eyes were closed, the respiratory 
movements did not entirely cease, but were reduced from 100 or 
110 to 8 or 12 per minute, and the creature was in a dormant con- 
dition. After exposure for a period of one hour, the web and the 
skin assumed a purple hue. After keeping the animal in such an 
atmosphere for If hour, it was in the same condition. 
