564 



RESPIRATORY APPARATUS IN BIRDS. 



337. 



verse septum. Sometimes this septum is carried a little more forward, and 



then the anterior reservoir is smaller ; this is most frequent in Palmipeds. 



At other times it inclines backwards, and the anterior reservoir is larger; 



this arrangement is peculiar to the 

 Gallinacfe. And, lastly,.this partition 

 divides the intercepted space between 

 the diaphragms into two equal 

 cavities : rapacious Birds offer 

 numerous examples of this. 



" Behind, these reservoirs stand 

 against the abdominal sacs, from 

 which they are separated by the 

 thoraco-abdominal diaphragm ; be- 

 low, they respond to the sternal ribs 

 and the lateral parts of the sternum ; 

 above, to the pulmonary diaphragm ; 

 inwards, to the thoraco-abdominal 

 diaphragm ; outwards, to the verte- 

 bral ribs and intercostal muscles. 



" A parabolic opening, situated in 

 the middle part of the external border 

 of the lung, or a little more behind, 

 establishes their communication with 

 that organ. This orifice, which is 

 remarkable for its great dimensions, 

 occupies the extremity of a volumi- 

 nous bronchial tube which follows 

 the direction of the generating trunk, 

 and in such a manner that this 

 trunk appears to pass directly to- 

 wards the posterior diaphragmatic 

 reservoir, and to open as a canal." 



6. Abdominal reservoirs (Fig. 337, 

 5). — "The two air-sacs situated in 

 the abdomen present themselves, 

 when inflated, as two enormous 

 bladders, the capacity of each diifer- 

 ing but little from the volume of 

 the trunk. Situated between the 

 superior and lateral parietes of the 

 abdomen on one side, and the abdo- 

 minal viscera on the other, they 

 cannot be dilated without driving 

 the intestinal mass downwards and 

 inwards. 



" Their anterior extremity, con- 

 tinuous with the lung, is somewhat 



inflected to pass under the fibrous arch extending from the spine to the pelvis. 

 " Their posterior extremity, dilated and voluminous, responds to the cloaca. 



Outwardly, they adhere by cellular tissue to the thoraco-abdominal diaphragm, 



6ENERAL VIEW OF THE AIR-RESERVOIRS OF THE 

 DUCK, OPENED INFKIUOP.LY ; ALSO THEIR RELA- 

 TIONS WITH THE PRIXJIPAL VISCERA OF THE 

 TRUNK. 



1, 1, Anterior extremity of the cervical reservoirs; 

 2, thoracic reservoir ; 3, anterior diaphragmatic 

 reservoir; 4, poste ior ditto; 5, abdominal reser- 

 voir, a, Membrane forming the anterior dia- 

 phragmatic reservoir ; 6, membrane formins; the 

 posterior ditto. 6. Section of the thoraco-abdomi- 

 nal diaphragm, d, Subpectoral prolongation of 

 the thoracic reservoir ; e, ])ericardium ; /,/, liver; 

 gf, gizzard ; h, intestines; ?«, heart; », n. section 

 of the great pectoral muscle abuve its insertion 

 into the humerus ; o, anterior clavicle ; p, pos- 

 terior clavicle of the right side cut and turned 

 outwards. 



