THE SALMON. 157 



the wood (that Birken Shaw is sinewy, tough, and 

 strong), cuts his rod, and laying about among the 

 " contributors," he " whips the offending Adam 

 out of them" in less than no time, and stating 

 the simple truth to the discomfited philosophers, 

 he broadly illustrates the difference between what 

 Wordsworth calls, " A Fact and an Imagination." 

 To resume. Mr. Shaw of Drumlanrig informs 

 us, that so far as his own observations go and he 

 in no way desires to gainsay the actual mews of 

 others, the trough or spawning bed is excavated 

 by the female alone, and by means not of the 

 snout, but of a peculiar action of the tail, by which 

 she both removes the gravel, and replaces it over 

 the eggs when these are laid.* The process of 

 laying usually occupies three or four days, and the 

 hatching of the ova is regulated in a great measure 

 by the temperature of the season. In severe 

 winters the principle of life is slowly developed. 

 Thus Mr. Shaw found by experiment, that ova 

 placed in a stream of spring water of the average 

 temperature of 40, exhibited the embryo fish 

 (visible to the naked eye), by the end of the 60th 

 day, and were hatched on the 108th day after 

 impregnation. Ova deposited by the same parent 

 on the same day in the river (the average tem- 

 perature of which for eight weeks had not exceeded 



* We may here note that the same observation or rather inference 

 had (unknown to Mr. Shaw) been made by Mr. Potts, in relation to 

 the Tweed salmon, as quoted long ago in Pennant's British Zoology. 

 That gentleman regarded the tail as the instrument by which the 

 gravel is displaced, in consequence of his having frequently found 

 that part rubbed or abraded, 



