MIGRATION AND HYBERNATION. 143 



mouths of the Thames and the Liffey, for in- 

 stance, yet, at least in the former river, are 

 compelled to relinquish their attempts to make 

 their way up on account, to our discredit be it 

 said, of the foulness of its waters. When these 

 shall be once more free from pollution and they 

 are slowly approaching this blessed state, thanks 

 to modern sanitation we shall once more restore 

 to these debarred ones their ancient home and 

 shelter in Father Thames. With the Liffey it 

 would appear things are not quite so bad, and, 

 remarkable as it may seem, the fish apparently 

 know that the polluted water is but local and of 

 a limited area, for they have been remarked to 

 charge this befouled region at full speed, and 

 successfully emerging in pure water, to lie quiet 

 for a few hours to recover from their exertions. 

 How is it, we may ask here, that since no fish 

 have been hatched in the Thames for many 

 generations, an effort is still made, or at least 

 contemplated, to gain the paradise of the quiet 

 upper reaches which lay far from the busy tur- 

 moil at the river's mouth ? Is there a tradition 

 of golden days within the sanctuary of this 

 grand old stream ? or is this yearning to ascend 

 to be regarded as a transmitted impulse *? 



The sturgeon is another denizen of the sea 

 though there are some fresh water species 

 that annually ascends the rivers to spawn. " In 

 summer, " writes Mr Lydekker, " regular fishing 

 stations are established on the Russian rivers, 

 where the approach of a shoal is heralded by a 

 watchman. Upwards of fifteen thousand have 

 been taken in a day at some of these stations ; 



