(7 , TIII: /,/:>///; i rimy i /'/' i /; i n x. 



p.iilit have li'-l US to tin- conclusion that llll tin- calialicllli open into mie another. Alld 



by this anastomosis constitute a i r\!ricab|c plexus who.-,e various parts column^ 

 with en -h other." 



Finally, it may be mentioned that "tin 1 \vnl Is of the pulmonary ca laliculi. e\a -nine I 

 microscopically, appear to be covered iuli-rnally with irregular septa which cin-nni -ci il>e 

 tin- iireolae, and give them a < llular a ; 



TUB AlU-SACS. 1 "In birds, the pulmonary mucous membrane is coiitinncil. at the 

 level of the orifices in the lung, into the utriciiliform cavities which nre developed 

 between the walla of the thorax and the abdomen on the on side, and tip- thoracic and 

 abdominal vi.-ccra on the other. These air-rc<crvoirs exist in all the vertehrata of the 

 second class. In all, they are situated at the periphery of tin- \isivra in the trunk, in 

 such a manner that Cams hns justly observed that the lungs of birds inclo-e all the 

 other viscera ; so that when they are distended by tin- entrance of air, the\ gem-rally 

 depress these viscera by pushing them towards the medi ,n plane. In ail. th 

 independent of each oth T, nnd freely communicate either with th lunic by a Hiiirlo 

 aperture, or with the bones by one or more openings. Lastly, in all they are nine in 

 number. 



"These reservoirs are : the thoracic sac, situated at the anterior part of the thorax ; 

 two cervical reservoirs, situated at the base of the neck; two ant<-ri<ir <//II/<//I-K;////.I//V > 

 reservoirs, placed between the two diaphragms; two posterior diaphragmatic reor\ 

 also between these two diaphragms, but behind the preceding; and, la-tl\ 

 altdominal reservoirs, placed against the superior wall of the abdomen. Of tin- 

 reservoirs, the first only is single and symmetrical; the others are pairs, and similarly 

 arranged on each side of the median plane. 



" The thoracic and cervical reservoirs tire situated beneath, and in front of, the lungs : 

 the abdominal reservoirs lie behind these organs, and the four diaphragmatic MCS at 

 their inferior part and between the preceding; heii"e the denomination of middle. 

 reservoirs sometimes applied to the latter, in opposition to the first, which are named the 

 anterior reservoirs, and to the second, called the posterior reservoirs." 



;\AL COXFOUSIATION OF THK llKsKuvoius. 1. Thoracic reservoir (Fig. 246, 2). 

 " It is situated above the clavicles and the inter-clavicular spare, in the cavity pi the 

 thorax, which it extends beyond on each side to the roots of the win','-, around the 

 articulation of the shoulder. It is related with : above, the trachea and o^ophagus on 

 the middle plane, the lungs and the origin of the cervical reservoirs on the lateral ; 

 below, with the sternum, the clavicles, and the interclavicular aponeurosis ; behind, 

 with the heart and anterior diaphragmatic reservoirs, beneath which it is prolonged by 

 forming on each a long point ; in front, with the integuments of the neck, which ii 

 into a hemisphere in Palmipeds, but which is angularly depressed in other classes ; mi 

 the sides, with the sternal ribs, the two clavicles, and the membrane uniting them. 



" The prolongations which arise from the lateral parts of these reservoirs, and 

 the walls of the thorax to pass around the articulation of the shoulder, are three in 

 number, and may be distinguished into inferior or subpectoral, suj>crior or subscapular, 

 and middle or humeral. 



"The subpectoral prolongation (Fig. 246, d) issues from the thoracic reservoir by an 

 orifice situated behind the posterior clavicle, and passes beneath the tendon of the great 

 pectoral muscle, where it spreads out as a lenticular cavity. The relations it contracts 

 with that muscle are remarkable: in birds, still more than in Man and a great number 

 of quadrupeds, the tendon of the great pectoral is formed of two parts, mic direct, tin- 

 other reflected ; it is between these two portions that this small uir-sac is insinuated, and 

 where it forms a very firm connection with them; the eflfe.-t of which is, that at the 

 moment the great pectoral muscle contracts, it dilates the subjacent cell and draws into 

 it a greater quantity of air. 



"The svLncapidar and humeral prolongation communicate with the principal reservoir 

 by a common opening placed behind the small adductor muscle of the humerus. 

 leaving this orifice, the subscapular sac spreads under the scapular and suliscapular 

 in nscle, which it separates from the ribs and corresiKmding intercostal muscles ; it is 

 developed in ire particularly in a longitudinal direction. 



" The humeral prolongation occupies the axilla ; it is smaller than the preceding, of a 

 pyramidal form, and opens by its summit into an infundibular fossa, which lead- t > tin; 

 canal of the humerus. 



"The thoracic reservoir differs from all the others by the extremely nun;. 



1 What is said relating to these air-sacs is taken from the Memoir of M. Sappcy 

 Kecherches Sur 1'Appareil liespiratoire des Oisc.iux,' Paris, 1847. 



