326 On the Temperature of Fishes. 



even more, abounded in blood, and that its muscles, generally 

 like those of the bonito, from the same cause, were of a dark red 

 colour. It immediately occurred to me, that its temperature 

 also might be high, and the result of careful inquiry amongst 

 the fishermen of most experience in the tunny fishery confirm- 

 ed the conjecture. All who were asked, declared that the 

 tunny is warm-blooded, and one of the most intelligent of them, 

 when questioned as to the degree of heat, said it was much the 

 same, or little less than that of the blood of a pig, when flowing 

 from the divided vessels of the neck in being killed. And this 

 man was very competent to give an opinion on the subject, hav- 

 ing been much employed in the fisheries on the Sicilian coast, 

 in which the viscera of the fish are the perquisite of the com- 

 mon fishermen, and are immediately taken out when the fish are 

 caught. 



From the tunny, I extended my inquiries to other fish of the 

 same family, and learnt, that the analogy holds good, applied to 

 all the species of the genus Thynnus of Cuvier and Valenciennes, 

 with which the Maltese fishermen are acquainted, viz., (besides 

 the two already mentioned) T. brevipinnis, T. thunnina, and 

 T. alalonga, all of which abound in blood, have a powerful 

 heart, red or reddish muscles ; and also, as I have ascertained 

 by particular examination, have their gills amply provided with 

 large nerves. Not having been able to procure any of these fish 

 alive, their exact temperature, of course, I have not been able 

 to determine ; but from the reports of the fishermen, it would 

 appear that the common tunny is the warmest of the species ; 

 and in accordance with this, I have found its branchial nerves 

 proportionally largest. 



These nerves (the branchial), immediately after quitting the 

 cranium, enter or swell cut into ganglia of considerable size, 

 and more or less connected together, from which five principal 

 trunks proceed, the first four chiefly to the branchiae, and are 

 the respiratory nerves ; the fifth, the lowest, to the branchise and 

 stomach. In point of magnitude, those respiratory nerves almost 

 rival the electrical nerves of the torpedo, and the^ origin is very 

 similar, and their direction and associations, but with this mark- 

 ed difference between them, that the torpedinal nerves are en- 

 tirely destitute of ganglia. 



