LUNGS 



279 



being that the bronchus enters a cavity, the atrium, which connects 

 with the chambers separated by the septa, and these in turn open 

 into a terminal vesicle, a condition recalling the parabronchi of the 

 birds, soon to be described. This resemblance is heightened by the 

 development in these same lizards of long, thin-walled sacs from the 

 posterior part of the lung which extend among the viscera, even into 

 the pelvic region. These air sacs, which are used to inflate the body, 

 foreshadow the similarly named structures in the birds. In the higher 

 lizards {Varanus, fig. 302) and in the turtles and crocodiles there 



Fig. 303. — Diagrams of {A) dorsal and {B) ventral aspects of lung of hen, after 

 Locy and Larsell. a, point of connexion of mesobronchus with abdominal air sac; 

 at, region of recurrent bronchi from anterior intermediate sac; at", connexion of anterior 

 intermediate sac with bronchus; b, bronchus; c, attachment of cervical sac; d, roots of 

 dorsibronchi; ec, ectobronchi; en, entobronchi; /, laterobronchi; Im, m, connexions of 

 lateral and mesial moieties of interclavicular sac; p, connexion of posterior intermediate 

 sac; r, retrobronchi from air sacs. 



is no atrium, the bronchus, on entering the lung, breaking up into 

 several tubes. As these connect with smaller tubes which lead to 

 the infundibula, the whole lung has a spongy texture. Also, in the 

 turtles the partitions are not vertical, but extend from medial- to 

 lateral side, and correlated with this, the entrance of the bronchus is 

 on the ventral side of the lung, not as in lizards (fig. 302) on the 

 medial side. 



BIRDS, — The lungs in the birds are closely connected with the 

 ribs and vertebral column and hence undergo less considerable changes 



