FISH. 



483 



from the tropical seas ; and yet cod, when taken there 

 at the depth of about forty fathoms, have an average 

 temperature of about forty-one or forty-two degrees, 

 or nearly that at which water has the greatest density, 

 though the water at the surface may be sixty degrees 

 or more. We are not aware that the temperature of 

 the water, at the depth from which the fish are taken, 

 has been observed at the same time with that of the 

 fish, but the surface temperature has ; and when we 

 consider that the whole, or at least the greater part, 

 is one current, we must conclude that at forty fathoms 

 or 240 feet, it must be considerably higher Uaan the 

 observed temperature of the fish. This is a process 

 on which it would be desirable to have many observa- 

 tions in different seas, and on different kinds of fish ; 

 because, as we cannot follow them in their submarine 

 abodes, and study them there, we should procure intel- 

 ligence of them by every means in our power. 



The changes of temperature in sea-fish, and even 

 in those of the greater part of the lakes and rivers, 

 must be but small, even in those places where the 

 surface freezes over. Water begins to freeze when 

 it is cooled after being stationary, or about 40 in the 

 mass ; and though the surface sinks to the freezing 

 point, and ice forms, the water below does not be- 

 come colder in consequence of the ice on tlie top. 

 No doubt the ice thickens at the under side in long 

 continued frosts, and the frost is sometimes of such 

 intensity and duration as that the whole volume of 

 an accumulation of shallow water is frozen ; but as 

 long as any portion of the water remains liquid, it 

 must, taken in the whole, be heated rather than cooled 

 by the ice over it. There is some portion of heat 

 produced in the act of freezing, and ice is a bad 

 conductor, and must increase the heat under it, so 

 that, as it. advances downwards in a continued frost, 

 it may be said to drive the action of the heat before 

 it. No part of the sea, or of any lake, or river oi 

 considerable depth, freezes to the bottom in any part 

 of the world ; and thus, the fishes in the sea mSy be 

 what we call very comfortable, even when the ice is 

 over them. 



It has sometimes been supposed that the fishes 

 hybernate in the depths, at those seasons and in those 

 places, where and when the surface of the water is 

 covered with ice. This may be true where the whole 

 volume of the water is, in consequence of its shallow- 

 ness, cooled down to 32 3 , and then of course the 

 whole mass will be frozen, and the fishes along with 

 it. But so long as any portion of the water remains 

 liquid, there is no more reason why the fishes shouh 

 Income torpid in it under an icy canopy than there 

 is for the Esquimaux becoming torpid in their snow 

 houses, in which they pass the winter with more 

 glee and hilarity than they do the summer in their 

 huts and tents. 



The idea of their not getting air under the ice 

 which is one of the usually-alleged causes of thei 

 hybernal torpor, is equally untenable. In a sinal 

 pond that has no communication with other liquu 

 water below the ice, this may be and often is the 

 case, but wherever there is a communication througl 

 liquid water to the sea, or any other extended surfae< 

 open to the air, there will be no want of air in th 

 liquid water, even though there should be a mile o 

 ice over it. The very cause by means ofwhicl 

 air gets at all mingled with the water, will mingh 

 it with all connected water, whether it happen 

 to be the part of the connexion which is open, or tha 



vhich is covered by ice. Indeed, if we are to 

 ose an inland lake, with a stream flowing from it, 



be covered with ice, and also the stream covered 



1 considerable way down, then upon the common 

 rinciple of the pressure of fluids, the liquid water 



,vhich is under the ice of the said lake, must become 

 sort of reservoir for air, and contains more than 

 he unfrozen water with which it has a liquid com- 

 munication. 



There is therefore, nothing, either in the altered 

 emperature or the absence of air, which can render 

 t necessary for the fishes in the arctic seas to be- 

 ome torpid in the water, though there may be 

 )hysiological causes which induce this in some, or 

 )erhaps in many of the species. As will be seen 

 on referring to the article EEL, the eels of even the 

 warmest parts of our own country pass the winter in 

 a sort of hybernating state ; but the cause is abso- 

 utely physiological : they seek shelter in the sand, for 

 the very same reason that brings them down to the 

 jrackish water in the autumn, namely, that the heat 

 may bring forward the germs of their progeny. 



When our common pond fishes are affected by loss 

 of air during the frost, they do not hybernate ; and it 

 would indeed be absurd to suppose that the depriv- 

 ing of any animal of air could be the means of 

 causing it to pass into any kind of sleep. Suffocation, 

 the effect of which is too painful to sleep under till 

 the operation has proceeded so far that the sleep is 

 the sleep of death, is what takes place in these cases ; 

 and difference of climate can, in this respect, pro- 

 duce no difference in the result. 



That many animals become torpid through cold, 

 and some at moderately high temperatures, is true ; 

 and though the occurrence is, in all probability more 

 rare, it is by no means impossible that animals may 

 be frozen and revive again after they are thawed ; but 

 this is a subject upon which many experiments have 

 not been made, and in those which have been made 

 the result has been failure. It is generally said, 

 indeed, and usually believed in America, that when 

 fishes are taken at the holes of the ice on the St. Law- 

 rence, during the intensity of the Canadian winter, 

 they are instantly frozen ; and that, while they are in 

 this state they are as brittle as the ice itself. Thus 

 far is most likely true ; for even in the comparatively 

 mild parts of this country, not only the leaves and 

 stems of plants, but the bones of animals when not 

 frozen, of course are much more easily broken than in 

 mild weather. But it is added that, if the frozen 

 fishes are put into cold water they are gradually 

 thawed and become alive again. An account of the 

 frozen eels carried to Moscow, will be found in the 

 article EEL, and gives (if true) some countenance to 

 the Canadian tale ; but the attempt has been made to 

 freeze fish and restore them to life again, in some parts 

 of North America at New York we believe where 

 it has failed. Hunter reduced the temperature of frogs 

 to 31 or one degree below the point of congelation ; 

 but we believe he did not in any case freeze them, 

 and unfrozen, a lower temperature than 31 always 

 occasioned death. Indeed there is another reason 

 for concluding that no animal, the blood of which 

 contains salts, especially muriate of soda, ran live to 

 be frozen and again revive, for salts, and the salt 

 which we have named especially, separate when the 

 liquid in which they are dissolved is frozen ; and thus 

 the probability is that freezing would decompose the 

 blood of a red-blooded animal. The eggs of birds 

 HH2 



