172 THE PRACTICAL FISHERMAN. 



gravity of the ova alone keeps them in their place till the spermatozoa of 

 the milt impregnates them. The male, in order to effect this, ascends to 

 a point a little above where the deposited eggs lie the distance is 

 determined by the rapidity of the stream and gently sheds the milt so 

 that it mingles with the water and falls upon the ova. He is supposed 

 to possess two spines in the ventral fins, by which he steadies himself in 

 the operation. This being concluded, the impregnated ova are lightly 

 covered up, and remain from eighty to 140 days unless eaten by old 

 unfecund fish before the embryo breaks the horny covering. 



Before passing away from this interesting branch of the subject I may, 

 perhaps, be allowed to jot down a few odds and ends in connection with 

 the ovum per se. First, as to the size. The size of the eggs of an adult 

 salmon are usually about that of a medium-sized pea, but I notice that it 

 varies slightly with the size of the fish. The colour is a beautiful opaline 

 pink, but the depth of this also varies with the habitat of the fish. The 

 ova of a Severn salmon, for example, is of an exceedingly rich deep colour, 

 whilst that of a Wye grilse is much paler. The colouring matter dis- 

 tinctly tints water in which they may be placed and stirred. When the 

 egg is exuded a tiny valve which closes from within is open. The 

 spermatozoa of the male remains remarkably active until it enters its 

 microscopical seed into the valve, which thereafter immediately closes, 

 and the egg becomes impervious to moisture until its vitality, from some 

 inherent or untoward cause, declines, when the valve again opens, and 

 water being absorbed, the ovum turns to a creamy white. The skin of the 

 healthy ovum is very tough until the latter days of impregnation, when 

 it, like a fowl's egg, seems to become more porous, and at least is capable 

 of being broken by the struggle of the confined embryo. As a proof of 

 the strength of the egg, I may mention that a weight of 61b. did not 

 burst, nor kill, a salmon egg on which I experimented, for it was 

 afterwards hatched, and the alevin lived for four weeks, only to fall a 

 victim to our voracious little friend the freshwater shrimp. 



The changes undergone by the egg towards vivification are very 

 gradual and interesting, and would well repay the time spent in micro- 

 scopically watching them. These are precisely similar in the case of 

 trout, reference to which is made in the chapter referring to them. At 

 last the incarcerated alevin becomes strong enough, and with one or two 

 terrible convulsions breaks through the restraint of his prison house, and, 

 as if delighted with the unrestrained freedom of a new existence, mounts 

 to the surface of the water, or strives to do so with a straggling 

 wobbling motion, and, having spent his superfluous force in this, falls 

 prone and exhausted to the bottom, where, behind a tiny stone or some 

 other convenient hiding place, it buries its head out of the light, as yet 



