8 



WILLIAM A. LOCY AND OLOF LARSELL 



also made an obvious growth. The bud (fig. 39) previously de- 

 scribed has divided into two main branches each of which has in 

 turn bifurcated, as represented in the figure. 



A second group of recurrent bronchi, also belonging to the ab- 

 dominal sac, begins early in the tenth day of incubation. The 



Cerv.Sc. 



Lat.moi. 

 Rec.Br. 

 Mes.moi. 

 Rec.Br. 

 -Pul.Vn. 

 A.lnt.Sc, 



Fig. 47 Ventral view of the uninjected luilgs of a ten and one-ha f day em- 

 bryo. Shows the air-sacs and their recurrent bronchi. The relations of the 

 mesial and lateral moieties of the interclavicular air-sac are well exhibited. 

 Rec.Br., recurrent bronchi, other reference letters as under figure 34. 



bud for this group starts at a point just dorsal to the base of the 

 first-formed group. At the close of the tenth day this outgrowth 

 (fig. 39) has bifurcated so that there is an anterior and a lateral 

 limb. The anterior limb curves gently upward. The lateral 

 branch makes a more sudden turn posteriorly. 



The eleventh day stage. The eleventh day stage is of some es- 

 pecial interest since it corresponds with Selenka's figure (78) in 



