OF NATURAL HISTORY. 8« 



cordingly, teaches us, that almoft all fifhes prey upon the fmalier 

 kinds, and even devour their own young. The liver is pioportion- 

 ally large, of a whitifli colour, and fituated on the left fide. The 

 gall-bladder lies at a confiderable diftance from the liver, and dif- 

 charges the gall into the gut. In fifhes, the organs of generation 

 are two bags fituated in the abdomen, and uniting near the anus. 

 In the male, thefe bags are filled with a thick whitifh fubflance 

 called the milt, and in the female with an infinite number of minute 

 eggs called the roe. At the feafon of fpawning, thej)ags of both 

 male and female are greatly diftended ; but, at other times, the male 

 organs can fcarcely be diftinguifhed from thofe of the female. 



The fwimming bladder is an oblong, white, membranous bag, 

 which contains nothing but a quantity of elaftic air. It lies clofe to 

 the back-bone, and has a pretty ftrong mufcular coat. By contrac- 

 ting this coat, and, of courfe, condenfing the air it contains, fome 

 fifhes are enabled to render their bodies fpecifically heavier than wa- 

 ter, and to fink to the bottom ; and, when the mufcular fibres ceafe 

 to adt, the air dilates, and makes their bodies fpecifically lighter. By 

 this curious piece of mechanifm, the animals have the power of 

 finking to the bottom, or of rifing to the furface. According to the 

 different degrees of contradtion and dilatation of this bladder, fifhes 

 can, at pleafure, keep themfelves higher or lower in the water. 

 Plence flounders, foles, fkate, and other fifhes which have no fwim- 

 ming bladder, alv/ays grovel at or near the bottom. It is likewife a 

 confequence of the relaxation of this bladder, that dead filhes which 

 are furniflied with it uniformly rife to the furface. The air-bag, 

 in fome fifhes, communicates, by a duft, with the gullet, and, in 

 others, with the flomach. At the upper end of the air-bag, there 

 are red-coloured glandular bodies conneded with the kidneys. From 

 the kidneys the ureters proceed downward to their infertion in the 

 t L urinary 



