80 THE SEAS 



These drifting eggs are to the naked eye like little glass- 

 clear balls, varying in size from that of a small pin's head 

 to about that of a radish seed. When first cast out into the 

 water the eggs of many kinds of fishes are indistinguishable 

 save by slight differences in size. But after a few days the 

 young fish begins to form within the egg and there appear 

 upon it flecks of colour, black, yellow or red, generally so 

 disposed on the body of the fish as to make the different 

 species quite distinguishable (Plate 29). There are, in 

 addition, in many eggs, globules of oil which either by their 

 size, number, or colour, make it at once apparent to which 

 species they belong. Thus to the specialist the identification 

 of fishes' eggs becomes no harder than does that of the 

 birds' eggs on land, the only difference being that it gener- 

 ally has to be carried out under the microscope. 



The eggs of the Angler Fish (Lophius piscatorius) present 

 a striking contrast to these single drifting eggs. In this 

 case the eggs are kept together in a large ribbon of jelly, 

 which may float at the water surface. Egg masses of the 

 Angler Fish have been reported several square feet in ex- 

 tent, flat expanses of jelly carrying millions of eggs. 



Practically the only one of our food fishes which does not 

 lay drifting eggs is the herring. The herring's eggs are 

 deposited on the sea floor, in certain localities only, on 

 stony ground (Plate 112). The eggs are sticky and cling 

 together in clumps in the crevices between the stones 

 among which they fall. They are much enjoyed by other 

 fish as food, especially by the haddock (Gadus ceglefinus) ; 

 indeed, some of the spawning grounds of the herring have 

 been located by the fishermen owing to the presence in their 

 trawl catches of what they call " spawny haddock," that is, 

 haddock whose stomachs are packed full with the herring's 

 eggs. 



Many skates and dog-fishes have curious eggs, which are 



