528 HABITS ANI> ANATOMICAL STRUCTURE 
aperture on their approximate sides ; which opening com- 
municated directly with the great air-cells of the cavity 
containing the heart and other viscera of the bird. 
This deviation from the usual structure is not very ob- 
vious to the eye, until the attachment of one of the bron* 
chial tubes to the lungs is divided, and turned back ; when 
the septum of the lower end of the trachea is distinctly seen, 
fringed with a firm but delicate membrane, which is quite 
separated from that forming the approximate sides of the 
bronchial tubes ; and a probe can be at once passed into 
the bronchial tubes, without the rupture of any membrane. 
In dissecting the recent specimen, on 6th August 1825, 
when the lungs and bronchial tubes were still in situ, and 
merely exposed to view, I placed the whole under the sur- 
face of water ; and on blowing into the trachea, the air was 
seen to pass through these openings on the inner sides of 
the bronchial tubes. A fine bristle, blunted at the extre- 
mity by burning, was introduced into these openings, and 
afterwards they were found sufficient to admit a large silver 
probe. On 13th August the specimen preserved in spirits 
was carefully opened, in the presence of Dr Williams, in a 
somewhat different manner. After exposing the inside of 
the thorax, the heart was dissected away, and the bronchial 
tubes remained in their natural situation. We found a 
small cell freely communicating with the great air-cells, 
formed by a transparent membrane stretched over the 
bronchial tubes ; while through it we could distinctly per- 
ceive the patulous openings in the bronchial tubes, kept 
distended by the rings of these tubes, so as to receive a 
portion of either air or water passing from the trachea ; as 
we ascertained by placing the whole in a basin with water. 
It would not be easy to represent in a drawing these 
apertures in the natural position of the bronchial tubes; 
but their appearance, when the tubes and trachea are in- 
