1 $6 WONDERS OF ORGANIC LIFE. 



and southern parts of Europe is the reverse of 

 that which, according to this theory, ought to 

 have happened. It is known that this fish is 

 now taken even on some parts of our own 

 coast, in every month of the year. It is pro- 

 bable that the mackerel inhabits almost the 

 whole of the European seas ; and the law of 

 nature, which obliges them and many others to 

 visit the shallower w r ater of the shores at a 

 particular season, appears to be one of those 

 wise and bountiful provisions of the Creator, 

 by which, not only is the species perpetuated 

 with the greatest certainty, but a large portion 

 of the parent animals are brought within the 

 reach of man, who, but for the action of this 

 law, would be deprived of those species most 

 valuable to him as food." The salmon is, to a 

 certain extent, migratory. It leaves the ad- 

 jacent sea for the estuary, and the estuary for 

 the river — the motive for this change being 

 the selection of a fresh-water breeding-place ; 

 for although the salmon is a marine as well as 

 river fish, it commences existence in the clearest 

 portion of inland streams ; and what is more, 

 it never migrates far, in its ocean-ward visit, 

 from the embouchure of its native river. The 

 period of the year at which the salmon enters 

 the estuary and ascends the river, differs 

 according to the temperature of a given river, 

 which temperature is influenced by many cir- 

 cumstances. Some rivers are filled with sal- 

 mon far earlier than are others. In the autumn, 

 or early part of winter, salmon recede from the 



