MULLEU] THE AIR-SACS OF THE PIGEON 375 



The Primary Air-sacs 



The Sacci cervicales 



Synonyms 



Bertelli: Sacchi cervicali. 



Campana: Receptacle superieur posterieur. 



Colas: Sac trachelien. 



Fatio: Sacci cervales. 



Gegenbaur: Sacci cervales. 



Gouillot: Reservoirs supralaryngiens. 



Huxley: Prsebronchial air-sac. 



Jacquemin: Poches pneumatiques pectorales. 



Merrem: Bulla jugularis. 



Milne Edzvards: Sacci cervicales (Reservoirs cervicaux). 



Oiven: Cervical air-cells. 



Pagenstecher: Sacci prsebronchiales. 



Sappcy: Sacci cervicales. 



Stannius: Vordere thoracale Zelle. 



Tiedcmann: Cellula cordis posteriora. 



The two cervical sacs arise from the right and left ostia cer- 

 vicalia respectively. According to Selenka (1866, p. 181) they are 

 first visible in the chick on the nth day of incubation as diminutive 

 protuberances. Bertelli (1900, p. 162) says, regarding their origin 

 in this bird, "Al quinto giorno appariscono gli abbozzi dei sacchi 

 cervicali. Prendono origine dalla meta dorsale della periferia dei 

 tubi pulmonali. Si spingono in avanti prima nelle cavita pleurichi, 

 poi nel tessuta mediastinale e cosi raggiungono il collo." The two 

 (right and left) cervical sacs together form a morphological unit. 

 In the adult pigeon they are paired, quite symmetrical, and not in 

 direct communication with each other. The ostia cervicalia from 

 which they arise lie just behind the bronchus. As, however, these 

 sacs assume the form of dorsoventrally compressed canals, which 

 extend between the pleura and the lung towards the anterior pul- 

 monary wall, the ostia seem, when the pleura is not removed, to lie 

 at the end of the medial third of the anterior margins of the lungs. 

 From these (apparent) ostia the sacci cervicales extend forward, 

 forming two lobes which are closely attached to the ventral and 

 lateral surfaces of the muscles of the neck (figs. 7 and n, SC; fig. 

 2, SC). These sacs are small. Their medio-dorsal surfaces touch 

 the ventro-lateral musculature of the neck, their latero-ventral 

 surfaces are parallel to the medio-dorsal ones, and touch the diver- 

 ticulum cesophageo-tracheale, the diverticula subscapularia of the 

 interclavicular sac (figs. 7 and n, DOETR), the oesophagus (fig. 7, 

 OE), the trachea (figs. 2, 7, n, and 12, TR), the vagus nerves and 



