and mechanical Action of the Muscles of Fishes, g 
size of a millet-seed, containing a white substance like the 
carbonate of lime found in the intercostal ganglions of frogs. 
This vesicle is included within the sheath of the nerve. 
The coats of the blood-vessels are of a delicate texture, 
and easily ruptured. In order, therefore, to secure them from 
being injured by the violent and sudden actions of the 
muscles, the principal trunks both of the arteries and veins 
are inclosed in osseous canals, formed by the bases of the 
superior and inferior spinous processes ; and their first rami- 
fications lie within grooves in the spines. As they pass out 
to supply the muscles, their branches are immediately subdi- 
vided, so that a considerable vessel soon becomes extremely 
minute. 
The rate, at which many fishes move through a medium 
so dense as water, is very remarkable ; their velocity being 
scarcely surpassed by the flight of the swiftest birds : and 
although the large proportion of muscles, and their advan- 
tageous application, may partly account for the phenomenon, 
yet the power would be inadequate to the effect, if it were 
not suddenly enforced ; as is evident from the slow progress 
of eels, and such fishes as are incapable from their length, 
and flexibility, of giving a sudden lateral stroke. 
But the quickness and force of action in the muscles of 
fishes are counterpoised by the short duration of their powers. 
Those accustomed to the diversion of angling, are aware 
how speedily the strength of a fish is exhausted, for if, when 
hooked, it be kept in constant action, it soon loses even the 
ability to preserve its balance, and turns upon its side, fatigued 
and incapable of motion. This has been vulgarly attributed 
to drowning, in consequence of the mouth being closed upon 
mdcccvi. C 
