472 Transactiom. — Miscellaneous. 



unless it has plenty to eat. But my difficulty is, within reasonable bounds, 

 in Bach a paper as this, to do justice to what I have sketched out in my pre- 

 ceding remarks. And not only so, but without a knowledge of what I have 

 yet to say, and which overlaps in many ways the former, these former 

 statements themselves would be practically unintelligible. I may, however, 

 here describe as shortly as possible these relationships between inert matter 

 and trout life, and leave further and fuller details to what has to follow 

 when they become necessary in dealing with the growth and habits of our 

 trout. 



The geological formation of a river's water-shed, then, is the basis or 

 origin of nearly all loose rocks, stones, gravel, sand, clay, and loam, which 

 form the banks or bed of that river. According to the nature of the soil in 

 the vicinity of a river, so is its fertility or otherwise — altitude, climate, and 

 exposure being also factors. The fertility determines the abundance of 

 vegetation, on the land and in the water, and that the supply of insect life, 

 of molluscs, crustaceans, etc., all the staple food of our trout. 



Again, the meteorological influences at work are by no means con- 

 temptible. Heavy floods in the spring or winter before the ova begin to 

 hatch out are believed to tear up and wash away the spawning beds or 

 " redds." Lowness of rivers, with frost, after spawning, is also fatal to 

 ova, but that is not likely to affect many of our waters. Floods, however, 

 must also wash away and kill the eggs or larvae of aquatic insects, as well 

 as of the Ephemera and Diptera (the flies of our summers), so injuring the 

 food supply of the future. On the other hand, droughts during summer in 

 very warm weather, result in the growth of low organisms, Fungi, and Alga?, 

 especiaUy, but not necessarily, where there is bed-rock. Anglers know too 

 well here the ugly green weed they name " blanket weed," which entangles 

 their lines at every cast ; and although it may contribute to the production 

 of minute species of fish food, it must sicken and cannot improve the health 

 of our trout. Wind, too, by its agitation of long deep pools, causes a mud- 

 diness of water, and drives all surface food to leeward, killing it at the same 

 time. Certain winds on some waters have a marked effect in contributing 

 to the feeding or the prevention of feeding in trout. 



In like manner much might be wrjtten on the consequences of changes 

 in atmospheric pressure, which there is reason for thinking have a good 

 deal to do with the times when trouts are on the move. So, also, as to the 

 essential health-preserving qualities of water which contains plenty of air in 

 solution, and of common salt. But I must now proceed from these con- 

 siderations, to gather together and lay before you the actual position of 

 the trout experiment in our waters at the present time under these 

 conditions. 



