126 Mr. Edmonston on the Origin of the Power of suspending 



Apparent JR. App'. Dec). 



aCew^OHn, June 26, 1822, Sabine, 14'>28"'13^' 60° 6' 33" 



Fallows, 14. 27 40 -8 60 5 54- 



Rumker, 60 6 3 



aPavoriis, July 31, 1822, Sabine, 20 11 36 57 17 34- 



Fallows, 20 11 37-3 57 17 30 



aGruis, Sept. 2,1822, Sabine, 21 57 3 47 48 35 



Fallows, 21 57 4 -2 47 48 42 



Achevnar, Sept, 30,1822, Sabine, 1 31 7 '5 58 8 7 



Fallows, " 1 31 9-3 68 8 11 



Rumker, 58 8 8 

 Edinburgh. July 11, 1827. 



XXV. On the Origin of the Power of suspending Respirationy 

 possessed by Aquatic Mammalia and Birds. By Lawrence 

 Edmonstox, Esq.* 



TO determine the nature and conditions of that power which 

 certain species of aquatic animals possess of suspending 

 respiration for a considerable time, has long been an interest- 

 ino- object of physiological investigation ; but the most accurate 

 observations and ingenious experiments seem hitherto to have 

 failed in removing the obscurity in which this singular phae- 

 nomenon is involved. Can this have arisen from the erroneous 

 direction in which research has been conducted ; or can it re- 

 sult from the insui'mountable difficulty of the subject? Has 

 the obvious suggestion been sufficiently attended to, that this 

 anomaly of respiration may constitute one of those ultimate 

 facts in the laws of vitality which, in its nature, may be inde- 

 pendent of peculiarity of organization ? 



We observe certain diving animals that breathe through 

 luncrs, as whales, seals, and water-birds, remain long under 

 water at one time, and not merely in a state of quiescence, 

 but often expending great muscular exertion. We know 

 that a much shorter period than this, without respiring, must 

 be necessarily and immediately fatal to land-animals similarly 

 formed ; and we are then too hastily disposed to infer, that 

 this singular faculty which aquatic animals joossess, must de- 

 pend on some undetected peculiarity of structure. The pro- 

 blem was supposed to have advanced towards solution, when 

 it was asserted that, in aquatic animals, \\\& foramen ovale re- 

 mained open, and that in them there was something analo- 

 gous to foetal circulation. 



But in the first place, it is unproved that in them the^ra- 

 meii miale is oftener open than in land-animals ; and, in the 



* Coniaiunicated b}- the Author. 



numerous 



