78 Contributions to the BiolofHf of Freshi rater Fishes 



At the base of this hill a large number of sphagnum bogs occur and 

 the water passing through these bogs, though perfectly clear, has a very- 

 detrimental effect on fish-hfe as repeated experiments have shown. 



It does not seem to make much difference whether the experiment 

 is tried before or after a period of drought, or in spring or summer, the 

 result is the same, and yet not a yard separates the burn from the bog- 

 water at some places. 



Before deforestation of the hillside, the surface water was allowed to 

 mix with that of the burn water running into the hatchery, but on account 

 of its deadly character an extensive process of draining has been under- 

 taken to prevent any of it reaching the water of the hatchery. 



It may be a coincidence, but the altered character of the surface 

 drainings since deforestation is very marked. 



In a later paper I hope to deal more fully with this sphagnum water. 



Bloom. 



The symptoms of this disease have already been mentioned. It can 

 easily be removed by putting the fry into a solution of common salt 

 about 5 per cent, strength, but the bloom soon returns if the fish are 

 put back into the same water from which they were drawn. 



Microscopic examination of the bloom gives no clue as to its com- 

 position as it appears as a homogeneous mass of sHme, no bacteria are 

 present, nor do cultures from this slime give any positive results. 

 Chemical investigations show it to be coagulated mucous due to the 

 high acidity of the peat water at times, and the presence of vegetable 

 toxins. 



It has been stated that the hatchery is served by two streams, one 

 draining a small area and the other a larger one. Taking the acidity of the 

 two streams after a period of normal steady weather, and using phenol- 

 phthalein as indicator and boihng the samples before titrating, the acidity 

 of the two streams calculated as sulphuric acid give : 



Stream from large area, 3-62 parts acid per 100,000 

 Stream from small area, 1'03 ,, ,, 



It was found necessary to use N 100, NaOH and 200 c.c. quantities 

 of water to get a good end point of the acidity. 



It is found that the acidity varies considerably over long periods; 

 given a period of settled weather the acidity rarely varies from the above, 

 but after a storm (say two or three hours) the acidity drops quickly for 

 about an hour, then rises quickly ; within an hour I have known it rise 



