THE EMBRYOLOGY OF THE BIRD's LUNG 41 



Juillet ('12) is very drastic in his criticism of several of Fischer's 

 observations and of this one in particular he says: ''G. Fischer 

 ('05) a donne des bronches diaphragmatiques une discrij)tion 

 assez confuse et a laquelle il y'a plusieurs reproches a faire 

 . . . . Le sac interclaviculaire s'ouvre d'apres lui sur ce 

 ranieau" (lateral or transverse branch) ''bronchique: I'orifice 

 qu'il signale ici est tres certainement I'orifice recurrent de ce sac 

 dont il a nial saisi les rapports exacts," etc. 



Howe\'^er defective Fischer's observations may be on other 

 structural matters (as Juillet claims), on this point, in particular, 

 our observations indicate that Fischer is probably correct. At 

 SLuy rate, we \vd\e found the orifice in question in the embryo 

 chick and also in the adult. In our preparations there are several 

 that show both direct orifices, the lateral and the medial, of the 

 interclavicular sac as in the Wood's metal cast of which figure 45 

 is a photograph. Moreover, the existence of a separate lateral 

 moiety implies, at least in the embryo, a direct opening from that 

 moiety into the lung. In this criticism Juillet overlooks the 

 fact that the direct connection between the curvilinear branch of 

 the first entobronchus and the interclavicular sac has been 

 indicated by a number of observers, as Huxley ('82), Baer ('96), 

 Lillie ('08), Schulze CIO). Accordingly, the claim of Fischer was 

 neither novel or unique. A further claim of Fischer, as Juillet 

 points out in the same paragraph, is that the curvilinear branch 

 of the first entobronchus has also a direct opening into the ante- 

 rior intermediate sac. On this point of the criticism our obser- 

 ^'ations lead us to agree with Juillet that such an orifice is lacking. 



Juillet's Schema (fig. X, p. 313), to show the relations of the 

 air-sacs and their recurrent bronchi with the ventral face of the 

 right lung of a chick embryo of the tenth day is faulty in show- 

 ing the interclavicular sac with a wide lateral extension crossing 

 the lung transversely and giving rise to recurrent bronchi. The 

 interclavicular sac at this stage of development (and for several 

 days thereafter) has separate lateral and mesial moieties as 

 shown in figures 47 and 49. The recurrent bronchi of the inter- 

 clavicular sac sprout from the lateral moiety, while, so far as we 

 have been able to determine, the mesial moiety never has any. 



