The Mechanisin of Pulmonary Eespiration 

 in Amphibians with Grill Clefts. 



By 

 H. L. Brunei-, Ph. D., 



Professor of Zoology, Butler College. 



With 11 figures in text. 



Contents. p age 



Introduction 63 



Physiological Observations 64 



Acquatic respiration 64 



Pulmonary respiration 65 



The Respiratory Mechanism 68 



The closing of the mouth 68 



The closing of the gill clefts 69 



The closing of the nasal passages 71 



The choanal valve of Necturus 72 



The choanal valves of Siren 74 



The choanal mechanism of Amphiuma 76 



Hitherto undescribed muscles in Amphiuma 77 



The closing of the choana in Cryptobranchus 79 



The choanal valve of larval amphibians 80 



Summary and Comment 81 



Bibliography 82 



Introduction. 



Cüvier (1805) accepted Townson's description of the respiratory 

 mechanism of the frog (1794) and Salamander (1795) and advanced 

 the view that the same sort of mechanism exists in amphibians with 

 gill clefts. In reply to the objection that such a mode of respiration 

 would be impossible because the air would escape from the gill 

 clefts, Cuvier (1810, 1836) showed that the axolotl and Siren are 

 provided with special muscles for closing the clefts. Fischer (1864) 

 found similar muscles in Necturus, Amphiuma and Cryptobranchus, 



