RESPIRATION OF TETRAPODS 

 (1) (2) 



45 



Fig. 13. 

 Diagrams to show four stages in the pulmonary ventilation of a 

 frog. Full lines indicate 'fresh' air; dashed lines — used air. Thick 

 arrows show the major movements, probably active, during each 

 phase. 



a4ma/iiw\mi^^ 



J — LJu 



12 3A 



t r f t r I I f [ I I I I [ I 



Seconds 



Fig. 14. 

 Rana. Recordings of the movements of the floor of the mouth and 

 flanks during respiration. The regular bucco-pharyngeal movements 

 are interrupted by periodic ventilation of the lungs. The four phases 

 of fig. 13 are indicated in the faster recording of one such movement 

 cycle. 



