H&w to obtain it. 87 



growth of minute vegetable forms, varying in degree according to 

 the nature of the water and the general surroundings, but the 

 presence of some of the larger plants is greatly conducive to the 

 health of the fish. Livingstone Stone says : " Water plants 

 consume carbon and return oxygen. Trout consume oxygen and 

 return carbon. By putting plants and fish together, therefore, we 

 avail ourselves of one of Nature's great universal agencies, in 

 balancing vital forces against each other, and maintaining the 

 equilibrium on which the continuance of organic life depends." 

 Speaking broadly, this is so, and it must be remembered that 

 some plants produce more oxygen than others, and some afford 

 food and shelter to a much larger quantity of animal organisms, 

 and every trout culturist nowadays knows the value of mollusca 

 and crustaceans, and especially some of the lower forms of the 

 latter, including the entomostraca. 



The fly-fisher in comparatively barren lakes, knows how often 

 in the neighbourhood of patches of aquatic vegetation, the best 

 fishing is to be obtained. The cause of this should be noted. 

 Shelter, food, and a greater abundance of oxygen are temptations 

 which cannot be resisted by the fish, and consequently they are 

 sure to be found in proximity to the vegetation which produces 

 them. As on land so in water, some plants are more favourable 

 to the production of food than others, and these are the plants to 

 seek out and cultivate, due care being taken to study their life 

 history, and to avoid as far as possible those which might, by 

 spreading unduly, become a pest in the pond. There is one 

 plant (Anacharis alsinastrum) to which I have already just alluded, 

 which has been found such a pest in some places where it cannot 

 be kept under. It should never, on any account, be introduced 

 into waters where due control over it cannot be maintained. In 

 places where it can be kept down easily it is, however, a most 

 useful plant. I have seen some lakes very much spoiled by it, 

 becoming quite choked, and an excessive amount of decay taking 

 place continually, and rendering the water very unwholesome. 

 In these places it sometimes unaccountably dies out. I have 

 seen a pond quite cleared of it in this way for awhile ; but, a few 

 small pieces retaining vitality will commence growing again, and 

 spreading with rapidity, will soon choke the place up again. 



