484 



WILLIAM A. LOCY AND OLOF LARSELL 



towards the lateral border and a slender outgrowth at its tip 

 (Latjnoi.) foreshadows the lateral moiety of the interclavicular 

 air-sac. The medial branch extends transversely in the oppo- 

 site direction (fig. 37 Mes.br.). 



The further de^'elopment of the first entobronchus consists in 

 the subdivision of its lobes into smaller lobules. These, in turn, 

 elongate and give off branches that develop into the parabronchi 

 of the cephalic region of the lung. The first entobronchus is a 



- - Cerv.Sc. 



-f Br.-- 



- Lat.moi.- - 



D.Br. Entl--- 

 ' Mes.moi -- 



- Rec.Br.'- 

 - A.lnt.Sc.-- 



Ent. 3-- 



-- Ent. 4-- 



Lat. 3 

 ■Bur. 



Abd.Sc 



Fig. 36 Lateral view. (Reference letters as in figure 34) 

 Fig. 37 Mesial view. (Reference letters as in figure 34) 



very large and important part of the bronchial passages. Its 

 subdivisions supply the summit of the lungs (fig. 44) and also 

 give rise to two air-sacs, the cervical and the lateral moiety of 

 the interclavicular air-sac. 



Entobronchus number two (figs. 28 and 30, Ent. 2) has a simi- 

 lar origin to that of number one. It starts about the middle of 

 the sixth day of incubation as a bud from the dorsal wall (mesial 

 in the adult) of the intra-pulmonary bronchus. It grows rapidly, 

 so that, at five days, twenty hours (figs. 28 and 29) it has an 



