376 FISHES. 



By means of these apparatuses, it has heen thought that in conse- 

 quence of the different lamina being placed alternately with respect 

 to each other, there was generated something like a galvanic pile, and 

 that these animals could, at will, communicate to those who touched 

 or went near them, a true electric shock. This power is exhausted by 

 use, and the fish requires repose to be able to renew it. For those 

 fishes which have this endowment it is an efficient defensive weapon, 

 and it jirobably serves them also as an instrument for stunning-, if not 

 for killing, the animals on which they prey*. 



CHAPTER VIII. 



Organs of Generation of Fishes. 



The rays, squahxs, and chimoeras, which produce eggsof considerable 

 size, and frequently surrounded by very strong, horny shells, or which 

 bring forth live young, possess organs very much resembling those 

 of reptiles, for the production of the egg, and for its fecundation in 

 the interior, as well as for the time, long or short, during which the 

 egg, or the foetus remains within the body of the motlier. 



In other fishes, however, even in those which bring forth their 

 offspring alive, and which must be fecundated before they spawn, 

 the organs for the two sexes are found to be extremely simple ; that 

 is to say, in the female, tv.-o membranous bags, the walls of which, 

 being more or less mvilti plied by folds, contain in their thickness the 

 eggs, until the time arrives, when these eggs have obtained their 

 necessary development, and it is by rupturing the membrane which 

 retains them that they escape ; now, in the male, the two sacs hold in 

 reserve, an abundance of fecundating fluid, which has been secreted 

 by the glandular tissue of its walls. 



The ovaries of the ordinary fishes are variable both in their size 

 and in the number of lobes into which they may be divided. Some- 

 times one of them is completely obliterated, so that only a single 

 lobe is developed, and tliis is exemplified in the perch; most com- 

 monly, however, there are two, whose form is oblong or oval, and 

 whose internal lamina forms a larger or smaller fold, according as 

 it may be necessary for the eggs contained in it. 



In the lophius there are two enormous bags with very thin walls, 

 which only carry the eggs in the thickness of one of their sides. But 

 these eggs, are very numerous in those sacs, and except at the period 

 Avhen tiaey are laid, the small groups Avhich they form, appear to the 

 naked eye, just like so many little papillary eminences, such as we 

 find in the intestines. 



The viviparous osseous fishes, as the blennies, silures, anableps, 

 &c. differ in no respect whatever, as to the structure of their ovaries, 

 there being, in each, two bags formed by two tvmics, in an interven- 

 ing space between whicli the eggs arise. In the progress of their 

 enlargement, the eggs protrude, and jjroduce a swelling of the inter- 

 nal tunic, which then moulds itself as it were upon them so that 



• * The experiments of Williamson especially prove this, see vol. 65 of Trans- 

 actions. 



