A FISH FROM A PELAGIC EGG. 63 



15 mm. in June, a length somewhat at variance with the 

 condition, as above stated, on our shores. In July they mea- 

 sured 2 inches, in September 3 inches and a half, and in 

 October about 4| inches. The second year they attained 14 to 



16 inches in length. In artificial circumstances, as well as in 

 nature, it is found that gi-eat variation exists in the sizes of the 

 young fishes of the same age, and this vaiiation would not 

 seem to be related to temperature. 



At the stages just mentioned they now come under the 

 notice of both liner and trawler, for young cod 5 or 6 inches 

 in length occasionally take a haddock-hook, and those somewhat 

 larger (9 to 18 inches) occur in certain hauls of the trawl, 

 especially off a rocky coast like that of Aberdeenshire, south 

 of Girdleness, as well as on the hooks of the liners on rough 

 ground. Special trips, indeed, were, and perhaps are, made 

 by the liners for the capture of these yoving cod (termed 

 codling), and thus their numbers are kept in check. 



So far as present observations go, therefore, the young cod 

 in a free condition reach the length of from 4 to 10 inches the 

 first year, while in the second they attain from 10 to 20 inches 

 or more. It probably takes 3 or 4 years (and this is the 

 original opinion of Sars) or more, to reach full maturity and 

 a length of 3 feet or upwards ; though he mentions having 

 seen young cod a foot in length, with mature roe and milt in 

 the fish-market of Christiania. These, however, were probably 

 examples of the small race of cod characteristic of the ^ords 

 of Norway. 



The young round fishes, such as cod, haddock, and whiting, 

 of similar or nearly similar size, seem respectively to herd 

 together. Thus it happens that in certain hauls of both liners 

 and trawlers the majority agree in size. This is well known to 

 the liners, who in former days specially sought out the young 

 cod as already indicated. The same feature is observed in many 

 other fishes, and probably conduces to their safety. 



So far as known, the adult fishes of the three kinds 

 specially alluded to in the preceding paragraph (viz., cod, 

 haddock, and whiting) follow no very definite law in regard 

 to migrations, if we except the apparent congregation in 



