130 Zoological Proceedings of Societies. 
out from the lungs of the bird, and the volume of which was just equal 
to that of the oxygen absorbed. The bird was somewhat disturbed dur- 
ing the experiment, but recovered immediately and perfectly on being 
released from its confinement. 
In the fourth experiment, in which a Pigeon was made to respire a 
mixture of oxygen and hydrogen with a small proportion of azote (the 
oxygen being in the same proportion as in common air), it was found that 
there was no loss of oxygen; but that a quantity of hydrogen disappeared, 
and was replaced by an equal volume of azote. The authours observe, 
that birds have a quicker circulation of blood than other animals; and 
also, that they are more sensible to the stimulating effects of oxygen. 
LINNEAN SOCIETY. 
April 7, 1829.—Mr. Brookes exhibited a living specimen of Lacerta 
ocellaia from St. Michael’s. 
May 25.—At the anniversary meeting, Edward, Lord Stanley, was 
re-elected President ; Edward Forster, Esq., Treasurer; J. E. Bicheno, 
Esq., Secretary; and R. Taylor, Esq., Under Secretary; and Thomas, 
Marquis of Bath, W. J. Broderip, Esq., R. E. Grant, M. D., J. Lindley, 
Esq., and N. Wallich, M.D., were elected Members of the Council 
for the year ensuing. 
June 2 & 16. A paper was read On the Organs of Voice in Birds: 
by W. Yarrell, Esq, F. L.S., &c. 
The authour, pursuing his enquiries into the structure of the trachee 
of birds, describes in the present communication the muscles by the action 
of which the varied powers of the vocal organs of birds are governed. 
Their organs of voice consist of four parts: the glottis, or superior 
larynx, the tube of the trachea, the inferior larynx, and the bronchie. 
Great differences exist in the relative length of tube; and short trachee 
are found to produce shrill notes, as in singing birds, while long ones 
produce loud and harsher sounds, as in the wading and swimming birds. 
Strong, broad cartilaginous rings give loud and monotonous voices, and 
slender rings with large spaces between admit variety of tone. Some 
of these varieties result from the dilatation and contraction of the mem~ 
