10 THE QUESTION OF FISH GROWTH. [CHAP. i. 



be nearly the same with all kinds of fish eggs, the only dif- 

 ference perhaps being that the eggs of some varieties will 

 take a longer time to hatch than the eggs of others I will 

 now pass on to consider the question of fish growth. 



All fish are not oviparous. There is a well-known 

 blenny which is viviparous, the young of which at the time 

 of their birth are so perfect as to be able to swim about 

 with great ease ; and this fish is also very productive. Our 

 skate fishes (Kaire) are all viviparous. " The young are en- 

 closed in a horny capsule of an oblong square shape, with a 

 filament at each corner. It is nourished by means of an um- 

 bilical bag till the due period of exclusion arrives, when it 

 enters upon an independent existence." I could name a few 

 other fish which are viviparous. In the fish -room of the 

 British Museum may be seen one of these. It is known as 

 Ditrema argentea, and is plentifully found in the seas of 

 South America. But our information on this portion of the 

 natural history of fish is very obscure at present. 



There are many facts of fish biography that have yet to 

 be ascertained, and which, if we knew them, would probably 

 conduce to a stricter economy of fish life and the better re- 

 gulation of the fisheries. Beyond a knowledge of mere gene- 

 ralities, the animal kingdom of the sea is a sealed book. x~N~o 

 person can tell, for example, how long a time elapses from 

 the birth of any particular sea fish till the period when it is 

 brought to table. Sea fish grow up unheeded quite, in a 

 sense, out of the bounds of observation. Naturalists can 

 only guess at what rate a cod-fish grows. Even the life of a 

 herring, in its most important phase, is still a mystery ; and 

 at what age the mackerel or any other fish becomes repro- 

 ductive, who can say ? The salmon is the one particular fish 

 that has as yet been compelled to render up to those inquir- 

 ing the secret of its birth and the ratio of its growth. (See 

 Natural and Economic History of the Salmon?) We have 



