218 Proceedings of the Royal Society 
some in the act of separating from the corpuscle have been ob- 
served. The colourless corpuscles are contracted into globular 
masses after the action of ozone. The general effects resemble 
those produced by a weak acid, sucb as very dilute acetic acid or a 
stream of carbonic acid. 
5. On Ciliary Motion . — When the cilia of the common mussel 
(Mytilus edulis ) were exposed to the action of ozone, while bathed 
in the fluid contained in the shell (sea- water), no effect was observed. 
This is owing to the protection to the cilia afforded by the water. 
If a very small amount of water covered the cilia, their action was 
at once arrested. 
From the preceding experiments the following general facts 
m ay be stated : — 
1. The inhalation of an atmosphere highly charged with ozone 
diminishes the number of respirations per minute. 
2. The pulsations of the heart are reduced in strength, and this 
organ is found beating feebly after the death of the animal. 
3. The blood is always found in a venous condition in all parts 
of the body, both in cases of death in an atmosphere of ozonised 
air and of ozonised oxygen. 
4. Ozone exercises a destructive action on the living animal tis- 
sues if brought into immediate contact with them ; but it does not 
affect them so readily if they are covered by a layer of fluid. 
5. Ozone acts as an irritant to the mucous membrane of the 
nostrils and air-passages, as all observers have previously remarked. 
At the present state of this inquiry, it would be premature to 
generalise regarding the relation between physiological action and 
the chemical properties of ozone ; but we can hardly avoid pointing 
out that oxygen in this altered condition (0 3 = 24) is slightly denser 
than carbonic acid (C0 2 = 22), and that, although the chemical acti- 
vity of the substance is much increased, yet when inhaled into the 
lungs, it must retard greatly the rate of diffusion of carbonic acid 
from the blood, which accounts for the venous character of that 
fluid after death. If, however, the physiological effect of ozone on 
respiration were merely due to its greater density, then we would 
expect its behaviour to be analogous to that of an atmosphere 
highly charged with carbonic acid. This has been found to be 
the case, more especially as regards the diminished number of re- 
spirations per minute, and the appearance of the blood after death. 
