COMMON PIGEON. 



49 



anthropotomy, divides into an axillary trunk, which passes into the wing 

 together with the brachial nerves, and into the much larger arteria 

 thoracica externa which supplies the great pectoral muscles. The gizzard 

 is concealed from view by the right lobe of the liver and the posterior or 

 xiphisternal end of the sternum which supports and protects both these 

 viscera. The duodenal loop containing the pancreas, and the segment 

 beyond that portion readily recognisable as belonging to the duodenum 

 by its large calibre, form a rudimentary spiral coil. The distal end of 

 the loop and of the pancreas inside it are bent upon the proximal segment 

 next to the gizzard, and are in relation with the lower lobe of the kidney 

 on the right as the gizzard is with the lower lobe of the kidney on the left 

 side. The distal segment of the duodenum bends up at some distance 

 from its pancreatic loop and comes into relation with the right lobe of 

 the liver which is excavated to receive it. In the interval between these 

 coils of the duodenum portions of the two other convolutions characteristic 

 of Columbae show themselves. Of these the distal one is the smaller in 

 calibre ; it shows some Peyerian glands, and is connected with the 

 proximal portion of the duodenum by a lamina of mesentery much as is 

 the colon in the Rabbit (see Fig. 2, supra). The coil interposed between 

 the duodenal and the distal coil is much the longest and most distinctively 

 spiral of the three, but being placed dorsally to them is not seen in its 

 full extent till they are displaced 1 . The lung, which occupies a much 

 smaller space in the dorso-sternal plane than in mammals, and in an 

 ordinary dissection of a bird's viscera scarcely comes into view until either 

 the ribs are displaced a little outwards or the lobes of the liver a little 

 inwards, reaches backwards so far as to interpose itself for some distance 

 between the anterior lobe of the kidney and the os ilii. Anteriorly one 

 of the musculo-tendinous languettes which in the Bird represent the 

 diaphragm of mammals passes inwards from the rib to the covering of 

 the lung and interposes itself between the region of the anterior kidney-lobe 

 and that of the lung. The Bird's differs further from the Mammalian lung 

 in being lodged conformably to the intercostal spaces, and being indented 

 by the six unanchylosed ribs, instead of being freely suspended, as is 

 invariably the case in mammals, and divided into lobes, as is very ordinarily 

 the case in those animals 2 . Another and most important point of 



1 Upon the differences observable in the number and character of these coils Dr. Hans Gadow 

 has based a classification of Birds in two memoirs containing much valuable information, J. Z. xiii. 

 1879. 



2 That however different at first sight the topographical relations of the lungs, liver, and heart 

 may seem to be in Birds and Mammals respectively, they nevertheless are not essentially dissimilar, 

 may be seen from the fact that the technical works on the physical examination of the heart in man 

 speak of the 'difficulty of separating the adjacent edges of the heart and liver' by percussion, and of 

 the dulness produced by the apex of the heart being indistinguishable from that produced by the 

 convex surface of the liver below it. See e.g. French's Diseases of the Liver, New Sydenham Soc. 

 Trans. 1860, p. 30; Walshe, Diseases of the Heart, 1862, p. 42. 



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