The object of the author, in the investigation which he has undertaken, and of which some of the results are given in the present paper, is to establish a law of the animal economy, which he expresses in the following terms: “The quantity of the respiration is inversely as the degree of the irritability.” Other authors, such as Cuvier, attaching a different meaning to the term
irritability
, have stated this property, in the different classes of animals, as being directly proportional to the energy of the respiratory functions; the purposes of which they have considered to be those of restoring to the exhausted muscular fibre its contractile power. The author of the present paper regards animal life as consisting in two essential ingredients; namely, stimulus and irritability; atmospheric air being the principal source of the former; the heart, where it exists, being the principal organ of the latter; and the blood being the medium by which these are brought into contact. For the purpose of ascertaining the quantity of respiration in any given animal, the author contrived an apparatus, to which he gives the name of the '
Pneumatometer
'. It consists of a glass jar inverted over mercury, and over the mouth of a bent tube, by which it communicates with a water-gauge of one tenth the capacity of the jar. Annexed to this apparatus, but unconnected with it, is a glass ball, containing ten cubic inches, and terminating in a tube, bent at its upper part, and of the capacity of one cubic inch, and inserted into a wider tube containing water, so as to correspond in all its pneumatic conditions with the jar and its gauge, and to point out whatever changes may have taken place in the volume of the air examined in the course of the experiment, from circumstances extraneous to it, such as variations of temperature, or of barometrical pressure. The animal, whose respiration is to be examined, is placed on a stand and covered with a jar; and the carbonic acid produced is absorbed by pieces of calico moistened with a strong solution of caustic potass, fixed by a wire frame in the upper part of the jar. The animal, at the end of the experiment, is withdrawn under mercury, without displacing the jar; the space it had occupied is filled with an equal volume of atmospheric air admitted into the jar; and the volume of oxygen gas absorbed is estimated by the column of water which has risen in the gauge.
On the inverse ratio which subsists between respiration and irritability in the animal kingdom; and on hybernation
