On the Temperature of Fishes. 325 



della lode. 1 ' * Persuaded as these academicians appear to have 

 been, it was by only so doing that they could keep to another 

 excellent rule which they had set themselves, viz. to experiment 

 and relate, and avoid all disputation. 



Malta, November 4. 1834. 



On the Temperature of some Fishes of the genus Thynnus. 

 By John Davy, M. D., F. R. S., Assistant-Inspector of 

 Army Hospitals. -f- Communicated by the Author. 



It is commonly believed and asserted by naturalists, that 

 fishes generally, and without exception, are cold-blooded ; thus 

 Linnaeus, in his " Regnum Animale," characterizes them in re- 

 lation to their blood, by " sanguine frigido and Baron Cuvier, 

 our latest and highest authority, not only admits, but under- 

 takes to shew, that it must be so; thus in the chapter of his 

 " Histoire Naturelle des Poissons," on the general character and 

 essential nature of fishes, he says, " Ne respirant que par Pinter- 

 mede de Peau, c'est-a-dire, ne profitant pour rendre a leur sang 

 les qualites arterielles, que de la petite quantite dV>xigene con- 

 tenu dans Pair mele a Peau, leur sang a dii rester froid. ,1 § 



It was many years ago, on a voyage to Ceylon, that I first met 

 with an exception to this universally received opinion : it was in 

 the instance of the Bonito (Thynnus palamys, Cuv. and Valen.), 

 whose temperature was 99° of Fahr. in the deep-seated muscles 

 in the thickest part of the fish a little below the gills, when the 

 surface of the sea, from which it had just before been taken, 

 was 80.5, the difference being the remarkable one of eighteen 

 degrees and a half. 



This fact necessarily made a strong impression on my mind, 

 and a year or two ago, when examining the heart and gills of the 

 tunny of the Mediterranean (Thynnus vulgaris, Cuv. and Valen.) 

 my attention was recalled to it, on finding that the latter were 

 supplied with nerves of unusual magnitude ; that the heart like 

 that of the bonito, was very powerful ; that the fish equally, or 



" Saggi di Naturali esperienze fatte nelP Academia del Cimento, p. xxx, 



-\- Read before the Royal Society of London. 



$ Systema Naturae, torn. i. p. 18* 



§ Hist. Nat. des Poissons, tome i. p. 275. 



