310 THE FAMILY OF EELS. 



This illustrious physiologist remarks further, that the presence 

 of life allowed the vital heat to be lowered to two or three 

 degrees below the freezing point; but after this it resisted all 

 further decrease; and when the powers of life had become 

 expended by the exertion of thus resisting decrease, the creature 

 became frozen like any other dead matter. 



An Eel in a weak condition was found to have the heat of 

 its stomach at 44°, which Avas at the same time the temperature 

 of the air. It was then put into water heated to 65°, and 

 kept there for fifteen minutes; in which time the fish had 

 acquired the same heat as the water; and it was noticed that 

 a living and a dead Eel received an equal amount of heat and 

 cold in an equal length of time; and he appears to think that 

 if the whole body of a fish should become really frozen, it 

 would have become past recovery by thawing. As a frog was 

 found to be able to digest its food when the heat was at 60°, 

 but to have lost that power when it Avas below 40°, the same 

 appeared to be the case with the Eel; which circumstance will 

 explain what has been observed of this fish in captivity; and 

 in a short series of observations on the upward migration of 

 young Eels, we have noticed that they do not shew themselves 

 while the temperature of the stream is below the annual medium 

 temperature of the air. 



There is no need that our attention should be engaged in 

 giving an account of the surmises which were hazarded on 

 the subject of the productive organs of these fish, the error 

 of which was caused by the expectation of finding in their 

 bodies a close resemblance of the milt and roe of most othei 

 fishes, to which, however, their organs of propagation bear in 

 some particulars but a distant likeness. But their situation in 

 the body is the same, and both the milt and roe lie along 

 the course of the back in a double, thin, and convoluted 

 stripe, which bears the appearance of fat rather than an organ 

 embedding grains of seed, which are in reality enveloped in 

 an oily substance, the use of which appears to be to afford 

 protection against changes of temperature that might be hurtful 

 to the spawn before it is shed. That the small grains embedded 

 within this soft and greasy covering are truly the spawn of 

 the fish is proved by the examination I have been able to 

 make, as also by the inquiries of other observers. Thus a 



