44 SALT-WATER FISHES 



thousand eggs, crowding each of twice as many nets in the 

 season of 1902, in numbers as appalling as those captured in 

 half the number twenty years ago, we cannot seriously condemn 

 the demersal egg as constituting a danger to the survival of the 

 species. Touching the above-mentioned influence of the float- 

 ing egg on the distribution of the species, it cannot be denied 

 that the range of a fish which is of sedentary habits in later life 

 may be appreciably extended by floating ova and free-swimming 

 young, just as the young barnacle travels far and wide, while 

 the old one is a fixture. 



In addition to their small size — the eggs of many of our 

 important food-fishes measure in diameter less than ^2 in., and 

 that of the dab {Vleuronectes) is less than -^ in. — the eggs of 

 the majority of fishes are transparent, or rather translucent, 

 and all but invisible in sea water, particularly those which float 

 separately. That of the sole {Solea), however, has several 

 oil-globules and a segmented yolk, both of which conditions 

 tend to render it conspicuous ; and that of the pilchard 

 {Cluped) is more easily seen that it would otherwise be on 

 account of the wide space between the yolk-membrane and the 

 surrounding envelope, technically known as the " perivitelline " 

 space. It must not be thought that the size of the egg has 

 always a direct relation to the size of the fish. In members 

 of the same family more particularly there is great risk of 

 error in such an assumption, for the egg of the turbot 

 {Rhombus), for example, is smaller than that of the plaice 

 (Pleuronectes). 



The unfertilised eggs of a fish, which for table purposes 

 we call " hard roe," are the product of the female. The " soft 

 roe " of our herrings and other fishes is the milt of the male. 

 Fertilised eggs — that is to say, those which, having been 

 deposited in the water by the female, are acted on by the milt 

 of the male — are of course never available as food for man. 

 The milt of a single male fish is capable, under favourable 

 conditions, of fertilising the ova of several females on encounter- 



