472 SUPPLEMENT ON 



This rate of going would give 86,400 feet in an hour, and 

 suppose the faculty of making the tour of the globe in some 

 weeks. 



It is impossible for us to scrutinize with effect the mys- 

 terious means by which the Creative Power impels the in- 

 numerable hordes to their annual and regular emigrations ; 

 but we know that towards the end of autumn, exhausted, 

 meagre, and feeble, they redescend to the sea, to seek their 

 ancient and profound retreats, until the returning season 

 again calls them to reproduction. 



It is, in fact, the necessity of spawning which impels them 

 to enter the rivers. The females which inhabit these rivers 

 at the period when their ovaries have acquired their full de- 

 velopement, seek out a place convenient for deposition, and 

 rather in the small streams than in the large rivers, choosing, 

 by preference, a current not very rapid, and a bottom of sand 

 and gravel. We are told that in many parts of Scotland, not 

 content with having selected a place suitable for the deposi- 

 tion of their eggs, these provident mothers seek to arrange it 

 in the most favourable manner, by digging an elongated hole 

 from fifteen to eighteen inches long, into which they discharge 

 their burthen, and then cover it with sand with their tail. 

 This fact is also asserted with respect to many other coun- 

 tries, and Dr. Grant, who confirms it in the Memoirs of 

 Stockholm, adds, that in thus preparing the cradle of their 

 posterity, they agitate themselves so much as to wear their 

 ventral fins, and rub themselves so strongly against the 

 ground, that they detach small stones from it with violence. 



When the eggs have been abandoned by the female, the 

 male comes to fecundate them, an operation which takes 

 place generally in the night, or during thick and foggy 

 weather ; after this the eggs are developed more or less 

 quickly, according to the temperature of the climate, the heat 



