Royal Society. 453 



that whatever interferes directly wiiii the motion of the glottis re- 

 duces the voice to a whisper ; that any permanent opening or defect 

 of the velum, whicli prevents the distention of the pharynx and the 

 closing of the postericn nares, renders articulation defective j that 

 the obstruction or removal of the cells of the face deprives the voice 

 of its bod)' and clearness ; and that nervous relaxation of the 

 muscles of the throat is productive of great alteration in the voice. 

 Hence the author infers the necessity of the numerous nerves which 

 are distributed to these organs. 



February 23. — The reading of a paper, entitled, " On the Inverse 

 Ratio which subsists between Respiration and Irritability in the 

 Animal Kingdom ; and on Hybernation," by Marshall Hall, M.D. 

 F.R.S.E., communicated by J. G. Children, Esq. Sec. R.S. was 

 commenced. 



March 1. — Dr. Hall's paper was resumed, and read in continua- 

 tion. 



March 8. — The reading of Dr. Marshall Hall's paper, entitled " On 

 the Inverse Ratio which subsists between Respiration and Irritability 

 in the Animal Kingdom ; and on Hybernation," was concluded. 



The object of the author, in the investigation which he has un- 

 dertaken, and of which some of the results are given in the present 

 paper, is to establish a law of the animal economy, which he ex- 

 presses 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 di- 

 rectly 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 ^Pneuinatometer\ It consists of a glass jar inverted 

 over mercury, and over the mouth of a bent tube, by which it com- 

 municates 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 pneu- 

 matic conditions with the jar and its gauge, and to point out what- 

 ever 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 j)ressure. 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 potash, 



fixed 



