302 ADDITIONAL NOTES. 



the stomach itself so changed, effects, it may be inferred, of the 

 gastric fluid, as explained by John Hunter, in his well-known 

 paper, " On the digestion of the stomach after death." In ac- 

 cordance with the quickness of digestion and facility of assimi- 

 lation is, I believe, the manner in which the kidneys perform 

 their function. They appear to be comparatively inactive, 

 thereby allowing the greater portion of the azotised matter of 

 the food to be assimilated, and applied to the growth of the 

 animal. What a contrast is offered in the excreta of the swallow 

 and trout, when, as in summer, both subsist on flies ! Amongst 

 those of the fish it is difficult to detect the urinary secretion ; 

 whilst in those of the bird it is conspicuous and abundant, con- 

 sisting principally of lithate of ammonia; and this is the more 

 remarkable in the instance of the fish, as it is provided with a 

 urinary bladder. 



In connexion with the solvent power of the contents of the 

 stomach, and the tendency of the bile in the gall-bladder and the 

 contents of the intestines, readily putrescent, to penetrate and 

 taint, and so injure the flavour of fish, it may be well to caution 

 anglers, who wish to keep the fish they take for the table, to have 

 them eviscerated as soon as possible, and also to have them kept in 

 the coolest place that may be available. A good plan is to have 

 them packed, not in green grass, as is usually done, but rather 

 in- dry straw, dryness rather than moisture being most favour- 

 able to the keeping of them fresh, and on the same principle, 

 their inside should be wiped with a clean cloth before they are 

 packed. J. D. 



(Rivers suitable to the Grayling, page 178.) 



In confirmation of the greater delicacy of the grayling, as to 

 temperature, compared to the trout, and of its intolerance of 

 great vicissitudes of river-temperature, I may mention, that 

 though this fish is plentiful, even more so than the trout, in the 

 preserved parts of the Derbyshire Wye and Derwent, it is almost 

 unknown in the Lathkil and the Bradford, tributaries of the 

 Wye, abounding in trout, and as carefully preserved. All 

 attempts to introduce it into these streams have failed. Their 

 inaptitude has been attributed to a difference in the quality of 

 their water : it has been said to be harder, more petrifying ; but 

 this I have not been able to confirm by chemical examination 



