198 STRUCTURE OP FISHES. 



From a fourth fish, the pectoral and abdominal fins 

 Ivere cut off on one side, and it immediately lost th« 

 power of keeping the back upwards. The single fins were 

 expanded, but the fish swam obliquely on its side with the 

 remaining pectoral and abdominal fins downwards. 



From a fifth fish all the fins were remoTed. Its back 

 was kept in a vertical position, whilst at rest, by the ex- 

 pansion of the tail, but it rolled half round at every 

 attempt to move. 



From a sixth fish, the tail was cut off close to the body. 

 Its progressive motion was considerably impeded, and the 

 flexions of the spine were much increased during the en- 

 deavour to advance : but neither the pectoral nor abdo- 

 minal fins seemed to be more actively employed. 



From a seventh fish, all the fins and the tail were re- 

 moved. It remained almost without motion, floating near 

 the surface of the water, with its belly upward. 



These experiments were repeated on the roach*, the 

 gudgeon +, and the minnow ;{:, with similar results. 

 Differences be- The muscles of fishes differ materially in their texture 

 tween the tex- fj-Qm those of other animals : they are apparently more 

 muscles of fish homogeneous, their fibres are not so much fasciculated, 

 and other ani- but run more parallel to each other, and are always com- 

 '* paratively shorter. They become corrugatt^ at tho 



temperature of 156o of Fahrenheit, when their tendinous 

 and ligamentous attachments are dissolved, and their se- 

 rous juices coagulated. Under those circumstances the 

 muscles lose their transparency, and the lateral cohesion 

 of their fibres is lessened. 

 Mechanical But the mechanical arrangement and physiology of the 



*^'^?" W^r la^c^^^ muscles of the body of fishes constitute my present 

 of the lateral object. These parts have already been described in a 

 muscles. general way by Professor Camper, M. Vicq-d-Azyr, and 



M. Cuvier, to whom I am indebted for much useful infor- 

 mation. They have been denominated couches muscum 

 laires, by M. Vicq-d-Azyr§, and muscles laterals by 

 M. Cuvier||. The term used by M. Cuvier seems very 



* Cyprinus rutilus. f Cyprinus goblo. | Cyprinus phoiinus. 

 § Mem. etrangers de I'Academ. des Sci. de Paris. Tom. VII. 

 p. i8 et 423- 

 • g Lc^om d'AnatomIc comparce. Vol. I. p. 196. 



appropriate 



