494 



The anterior intermediate air-sac also has two groups of orifices. 

 The monobronchial direct orifice (fig. 8 and 9, d.o.a.i.) has already 

 been mentioned in connection with the corresponding orifice of the 

 sub-broncbial air-sac. The other and more ventral group is of the 

 polybronchial recurrent type. By a process similar to that described 

 in connection with the sub-bronchial sac, the originally single stem 

 of these recuiTent bronchi becomes expanded in such a manner that 

 its original branches open directly into the adult air-sac. The number 

 of orifices varies, but is usually five or six. The distal end of the 

 anterior intermediate recurrent bronchi are in connection with other 

 air passages in the latero-ventral part of the lung. 



Fig. 8. Fig. 9. 



Fig. 8. Diagram of ventral aspect of lungs on first day after hatching of 

 chick. Shows complete coalescence of two moieties of the sub-bronchial air-sac {S.l 

 and S.S) and partial coalescence of the two sub-bronchial air-sacs to form the one 

 large sub-bronchial sac of the adult fowl. Also shows the direct orifi^ces (d.o.) of the 

 air-sacs and the orifices (o.) of the recurrent bronchi. Other abbreviations as before. 



Fig. 9. Mesial view of right lung of one day chick. Lettering as in preceding. 



The posterior intermediate sac communicates with the lung by a 

 polybronchial group of orifices made up of both direct and recurrent tubes. 

 There is one direct orifice (fig. 8, d.o.) which is the opening of the 

 third laterobronchus from which this sac has its origin. The recuiTent 

 orifices (fig. 8 and 9, o.), (figures 8 and 9 represent the lungs of 

 a one-day chick, but the relation of the orifices is the same as in th& 



