THE COMMON BROWN TEOUT. 211 



snnlight, are, in their native stream, sometimes light and sometimes of a 

 dark hue. In truth, the variation seemed to occur often with no visible 

 reference to the effect of light. By the aid of the microscope, however, 

 the result seemed that, although the sunlight certainly could produce an 

 alteration of hues, yet the pigment cells under the skin were chiefly 

 affected in all cases by the health of the fish. Perfect sterility accom- 

 panied some of these visitations. 



A remarkable example of this variation is given by the author of "Wild 

 Sports of the West." "I never observed," he says, "the effects of 

 bottom soil upon the quality of fish so strongly marked as in the trout 

 taken in a small lake in the county of Monaghan. The water is a long 

 irregular sheet of no great depth, one shore bounded by a bog, the other 

 by a dry, gravelly surface. In the bog side the trout are of the dark and 

 shapeless species peculiar to Moorish loughs, whilst the other affords the 

 beautiful and sprightly variety generally inhabiting rapid and sandy 

 streams. Narrow as the lake is, the fish appear to confine themselves to 

 their respective limits, the red trout being never found upon the bog 

 moiety of the lake, nor black where the under surface is hard gravel." 

 This apparent stop-at-home instinct in the fish is, of course, accounted 

 for easily. The fish undoubtedly observed no arbitrary limits, but when 

 they had migrated and remained a short time over a different coloured 

 strata the colour no doubt changed, as in the case of the minnow 

 (described in the chapter on that interesting fish), and thus deceived the 

 angler into supposing them non-migratory. 



The impetus which has of late years been given to the culture of the 

 salmonidae of necessity renders it almost impossible to say anything new 

 on the subject of the personal history of this fish. A brief r^sumd, how- 

 ever, may be desirable. Trout generally are very fecund. Notwithstand- 

 ing the sterility of some, through the enervating effects of disease, the 

 trout, in a greater percentage of cases than any other fish, deposits its 

 spawn healthily, and with strict reference to a code of instinctive rules 

 from which it seldom deviates. Its spawning season varies greatly with 

 the mean temperature of the year. Sometimes the breeding may be said 

 to begin in some rivers as early as the end of August ; on other occasions 

 the ova is not deposited until January. In each situation, however, a 

 regular procedure is gone through. Like the salmon, the female, as 

 the period of gestation seems approaching its termination, ascends the 

 stream, surmounting obstacles of all descriptions, until a suitable position 

 is reached, when she commences turning up the gravel as might a hog. 

 The male fish are seldom far behind, and many and deadly are the combats 

 which frequently take place between them for the honour of assisting in 

 the operation of making this bed. On several occasions I myself have 



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