THE SALMOIf FAMILY. 329 



weight was as much as 9 lbs. in four years (or from 1 to 

 10 lbs.*). 



From the experiments on the different modes of fatten- 

 ing Trout above referred to, it is evident that fish and 

 grubs bear no comparison with insect-food in point of 

 nourishmentj doubtless in consequence of the amount of 

 phosphate of lime contained in the latter. Of the insects 

 specially contributing to the food of fish, probably the 

 most nutritious of all are the May-flies, upon which, 

 when arrived at maturity, the adult Trout wreak a signal 

 vengeance for the destruction effected by the larvae of the 

 one amongst the eggs of the other f — a retributive law of 

 nature, of which many curious examples occur in the 

 animal kingdom. 



The May-fly, or, as it is sometimes called, Day-fly 

 {Ephemera vulgaris), is well known to fishermen from the 

 immense numbers in which it suddenly appears upon the 

 rivers in spring, swarming over the water and waking into 

 voracious activity every living creature — feathered and 

 scaled — which preys above or below its surface. In such 



* One of tlie Trout (a female), wHch liad been regularly fed and 

 weighed during six years, being observed to be falling off in colour 

 and condition, was killed, and found to weigh 7 lbs. Its progi-essive 

 increase and its decrease are shown in the table : — 



Date of weighing. 1835. 1836. 1837. 183S. 1339. 1840. 



libs. oz. Its. oz. n>s. oz. Its. oz. Iba. oz. Its. oz. 



April 1....012..112..3 4.. 5 4.. 7 0..7 4 

 October 1..1 4.. 2 0..5 0..512..7 8.. 7 



New Sporting Magazine for Nov. 1840, p. 075. 

 t See p. 272. 



