1 88 MILLER. 



DESCRIPTION OF PLATE IX. 



Fig. 17. Reconstruction from sections of a lung lobule. X 50 times. The 

 model is divided through its centre, and is viewed towards the pleura. The tip of 

 the terminal bronchus is the colored yellow ; the atria are colored pink ; the air- 

 sacs and air-cells are dark. The upper arrow indicates an air-sac passage leading 

 from an atrium into an air-sac. The lower arrow passes through a vestibule into 

 an atrium and its point may be seen in an air-sac. 



Fig. 18. Reconstruction from sections of the lobule of the lung. X 50 times. 

 Fig. 17 and 18 are the two halves of the same model which has been cut in half 

 and its two cut surfaces exposed. The letters a and a, and h and b show how the 

 two figures can be placed over each other. The lobule is divided in the centre 

 and is the view towards the deeper portion of the lung. The colors indicate the 

 same as in Fig. 17. The dotted line separates two lobules from each other, and 

 just beneath it is the point where the bronchus bifurcates into the two terminal 

 bronchi. 



Fig. 19. The same as figure 17, showing only the terminal bronchus and the 

 four vestibules which arise from it. Yellow, termmal bronchus ; pmk, atria. X t^t, 

 times. 



Fig. 20. A portion of figure 17, in which only those air-sacs and air-cells just 

 below the pleura are shown. X 33 times. 



Fig. 21. A reconstruction corrosion of an atrium with a smgle air-sac attached. 

 X 50 times. V. vestibule ; A. atrium ; P. cut air-sac passage ; .5". air-sac. A cast 

 of an air-sac. X 50 times. 



Fig. 22. A cast of an air-sac. X 50 times. The figure shows the irregular 

 form of the air-sacs ; also a deep cleft nearly dividing it in half. This form is quite 

 common. P. air-sac passage ; S. air-sac. 



Fig. 23. Reconstruction corrosion of the lobule of the lung. X 33 times. At 

 X a divided vestibule is seen. An atrium and its air-sacs have been removed. 

 A. artery ; V. vein. 



Fig. 24. The atrium and its air-sacs which were removed from Fig. 23. X 

 33 times. X the divided vestibule. 



Fig. 25. Reconstruction corrosion of the lobule of the lung. X 50 times. All 

 the air-sacs of one side removed. B. terminal bronchus ; A} A? A? atria ; P. air- 

 sac passages ; S. air-sac (the same as in Fig, 21) ; Ay, artery ; V. vein. 



