FISHES IN GENERAL. 



611 



way will necessarily oblige it to make use of 

 all its hidden stores; and, as there is a com- 

 munication between the gullet and the air- 

 bladder, the air which the latter contains 

 will thus be obviously drawn away. But 

 still farther, how comes the air-bladder, ac- 

 cording to their hypothesis, to swell under 

 the experiment of the air-pump ? What is it 

 that closes the aperture of that organ in such 

 a manner as at last to burst it? or what 

 necessity has the fish for diluting it to that 

 violent degree? At most, it only wants to 

 rise to the surface; and that the fish can 

 easily do without so great a distention of the 

 air-bladder. Indeed, it should rather seem 

 that the more the air was wanted without, 

 the less necessity there was for its being use- 

 lessly accumulated within ; and, to make the 

 modern system consistent, the fish under the 

 air-pump, instead of permitting its bladder 

 to be burst, would readily give up its con- 

 tents ; which, upon their supposition, all can 

 do at pleasure. 



But the truth is, the fish can neither in- 

 crease nor diminish the quantity of air in its 

 air-bladder at will, no more than we can that 

 which is contained in our stomachs. The 

 animal has no one muscle, much less a pair 

 of muscles, for contracting or dilating this 

 organ ; its aperture is from the gullet ; and 

 what air is put into it must remain there till 

 the necessities, and not the will, of the ani- 

 mal call it forth as a supply. 



But, to put the matter past a doubt, many 

 fish are furnished with an air-bladder, that 

 continually crawl at the bottom; such as the 

 eel and the flounder ; and many more are 

 entirely without any bladder, that swim at 

 ease in every depth ; such as the anchovy 

 and fresh-water gudgeon." Indeed, the num- 

 ber of fish that want this organ is alone a suf- 

 ficient proof that it is not so necessary for 

 the purposes of swimming ; and as the ven- 

 tral fins, which in all fish lie flat upon the 

 water, seem fully sufficient to keep them at 

 all depths, I see no great occasion for this in- 

 ternal philosophical apparatus for raising and 

 depressing them. Upon the whol 3 , the air- 

 bladder seems adapted for different purposes 

 than that of keeping the fish at different 



Redi. 

 wo. 51 Hi 52. 



depths in the water: but whether it be to 

 supply them with air when it is wanted from 

 without, or for what other purpose, I will not 

 take upon me to determine. 



Hitherto we have seen fish in every respect 

 inferior to land animals : in the simplicity of 

 their conformation, in their senses, and their 

 enjoyments ; but of that humble existence 

 which they have been granted by nature, 

 they have a longer term than any other class 

 of animated nature. " Most of the disorders 

 incident to mankind," says Bacon, " arise 

 from the changes and alterations of the atmos- 

 phere ; but fishes reside in an element little 

 subject to change ; theirs is an uniform ex- 

 istence ; their movements are without effort, 

 and their life without labour. Their bones 

 also, which are united by cartilages, admit 

 of indefinite extension ; and the different 

 sizes of animals of the same kind, among 

 fishes, is very various. They still keep 

 growing; their bodies, instead of suffering 

 the rigidity of age, which is the cause of 

 natural decay in land animals, still continue 

 increasing with fresh supplies; and as the 

 body grows, the conduits of life furnish their 

 stores in greater abundance. How long a 

 fish, that seems to have scarcely any bounds 

 put to its growth, continues to live, is not 

 ascertained ; perhaps the life of a man 

 would not be long enough to measure that of 

 the smallest. 



There have been two methods devised for 

 determining the age of fishes, which are more 

 ingenious than certain ; the one is by the 

 circles of the scales, the other by the transverse 

 section of the back-bone. The first method 

 is this: When a fish's scale is examined 

 through a microscope, it will be found to con- 

 sist of a number of circles, one circle within 

 another, in some measure resembling those 

 which appear upon the transverse section of a 

 tree, and supposed to offer the same informa- 

 tion. For as in trees we can tell their age by 

 die number of their circles, so in fishes we can 

 tell theirs by the number of circles in every scale, 

 reckoning one ring for every year of the ani- 

 mal's existence. By this method, Mr. Buffon 

 found a carp, whose scales he examined, to 

 be not less than a hundred years old ; a thing 

 almost incredible, had we not several accounts 

 in oilier authors which tend to confirm the 



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