SALT-WATER FISHERIES OF NORWAY. 669 



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 All this is certainly correct, but it is a very rash conclusion to suppose 

 that this skin ever covers the whole eye, so that in the end the fish be- 

 comes entirely blind. With a view of ascertaining the truth in this mat- 

 ter I have examined maclierel both in the beginning of the fisheries 

 and later in the season, and it is my firm conviction that the mackerel 

 can see as well early in the year as later, although the above-mentioned 

 skin decreases in size toward summer. This skin is nothing else but 

 two folds of skin, which are also found in other fish {e. {^. the herring), 

 and which from both sides extend over the eyeball. These folds never 

 reach over the pupil of the eye, which, as is well known, is the only 

 channel through which rays of light can enter the eye. The faculty of 

 seeing would, therefore, not be aftected in the least, whether these folds 

 are transparent or opaque, whether they cover a larger or a smaller por- 

 tion of the opaque parts of the eye. The greater development and 

 smaller degree of opaqueness of these folds earlier and later in the year 

 are simply occasioned by the mackerel's being fatter at that time. In 

 the middle of summer immediately after spawning the mackerel is thin- 

 nest, and that fat which formerly was found in the above-mentioned 

 folds has therefore been absorbed, which of course has an influence on 

 their extent and transparency. A completely blind mackerel has never 

 been seen yet, and will never be seen ; and still it is by no means rare 

 to catch stragglers late in autumn and winter, or at that time when, 

 according to popular opinion, the mackerel ought to have lost its sight 

 long since. 



As long as it was supposed that the mackerel was blind in winter and 

 lay in a sort of torpor, it followed necessarily that it must keep on the 

 bottom. But as this, as I believe, is not only improbable, but an abso- 

 lutely foolish notion, we must again discuss the question regarding the 

 supposed place of sojourn of the mackerel when it is not near the coast. 

 The oldest supposition, given up long since (Andersson's), is, that the 

 mackerel came from the sea near the North Pole, and that from here 

 at certain seasons of the year a large school travels, south, like a swarm 

 of bees leaving its hive. This school was then supposed to pass through 

 the Polar Sea and the Atlantic Sea like a dense phalanx, and having 

 reached the heights of Europe to divide into smaller schools, each of 

 which sought a special part of the coast, to return by the same route 

 and spend the rest of the year in undisturbed repose under the ice of 

 the Polar Sea. Andersson's migration theory, which was applied not 

 only to the mackerel but also to the herring, has recently given way 

 to an entirely opposite theory, viz, that the mackerel is a stationary, 

 fish having its winter quarters in the deep places immediately outside 

 that portion of the coast where later in the season it comes to spawn. 

 This theory is in my opinion just as erroneous as the other. I have in 

 other places given my theory regarding the herring, according to which 

 I suppose that this fish leads a pelagian or roving life all the year round, 

 and is found in smaller or larger schools in different j)laces in the outer 

 sea wherever it finds most food. 



