450 WILLIAM A. LOCY AND OLOF LARSELL 



The observations are brought under consideration in the fol- 

 lowing order: 



1. The external aspects of lung development. 



2. The development of the bronchial tree. 



3. The air-sacs and the recurrent bronchi. 



4. The development of the pulmonary artery. 



Followed by comments on the steps of progress in the ana- 

 tomical analysis of the bird's lung and comparison of some of 

 our results with those of previous observers. 



Co7nments on the literature. In dealing with the extensive lit- 

 erature of the avian lung one is confronted with the dilemma of 

 choosing between a comprehensive chronological mention of the 

 observations of the different investigators or a very condensed 

 selective review of the results of a few workers. The latter plan 

 on the whole seems better, since the literature has been repeatedly 

 reviewed (as in Flint's contribution, '06, in Juillet's, '12, and in 

 the papers of others) ; moreover, genuine advances are contained 

 in a limited number of papers. 



As to embryological observations, the chief contributions are 

 by Rathke, '28; Von Baer, '28; Remak, '55; containing the first 

 figures of the buds of the ecto- and entobronchi; Selenka, '66, on 

 development of the air-sacs; His, '68, laryngo-tracheal groove and 

 trachea; Zumstein, '00, bronchial tree and air-sacs; Moser, '02, 

 method of growth; Bertilli, '05, air-sacs; Juillet, '12, compre- 

 hensive treatise; besides text-books, as Foster and Balfour '74; 

 Marshall, '93; Lillie, '08, etc. 



As to intra-pu monary anatomy of adult stages : Sappey, '47 ; 

 the bronchial passages especially analyzed by Campana '75; Hux- 

 ley, '83 bringing the terms mesobronchium, ecto, ento, and para- 

 bronchia into common use; F. E. Schulze, '09, '10, '11, bronchial 

 tree and air-sacs; Miller '93, comparative structure of lungs in- 

 cluding birds; Guido Fischer, '05; Juillet, '12. 



Histology: F. E. Schulze, '71; Oppel, '05. 



The air-sacs have been extensively described in the adult with- 

 out involving the anatomy of the lungs as by Guillot, '75, com- 

 parative; Bruno Miiller, '07, pigeon; Schulze, '10, etc. 



