INTRODUCTOEY. 41 



herrings, Imve made tlieir way 50 or 60 miles out to sea, 

 and then turned round and come back again. If not, 

 we must conclude that they began life far away from 

 where they should have been hatched, according to the 

 common idea. Again, if spawning had nothing to do 

 with the movement of these shoals from deep to shallow 

 water, or, at all events, towards the land, have we any 

 reason for supposing that such was the motive of those 

 fish which came in at the autumn spawning time ? 

 Such evidence as we possess seems to point to there 

 being more than one spawning season, and that the 

 spawn is deposited wherever the fish may happen to be 

 when it is ripe ; but why the herrings should make 

 periodical visits to the land, whether in spawn or not, 

 has yet to be shown. 



Precisely the same thing occurs with tlie mackerel ; 

 but M. Sars has ascertained that with that fish the 

 spawn is frequently shed far out at sea, and in very 

 deep water. As before mentioned, the ova of the 

 mackerel float at the surface, and there is no occasion 

 therefore to seek any suitable bed for them. Yet the 

 mackerel gradually makes its way inshore in precisely 

 the same manner as the herring does ; and half-grown 

 fish without any roe are often as numerous among the 

 moving shoals as those which are full of spawn. The 

 great body of pilchards appear on the Cornish coast 

 after they have spawned in deep water ; but a few, appa- 

 rently of different shoals from the very large majority, 

 are in spawn when near the land in autumn. We find 

 the same thing happening in the case of sprats, fish of 

 almost every size being caught in the same week — we 

 might almost say on the same day — some with the roe 

 in various stages of growth, and others with none to 

 be seen. We might go through the whole list of our 



