WHITEFISH OF THE LAKE OF GENEVA 



watercourse, however limpid and pure, if circumstances 

 prevent it from having an adequate average sitesis. 



When we see a broad and mighty stream from which 

 the local fishermen daily take a goodly number of 

 fish; when we consider the ease with which these 

 fish, hitherto unseen and hidden, are taken from it, 

 we cannot help thinking that the water might hold 

 more and produce more, taking into consideration 

 the extent and depth of the space in which they live. 

 It looks as though this space alone counted, and that 

 its vastness might easily contain more than the pro- 

 duction we actually secure and consider rather low. 

 But if the water contains, if it might contain still 

 more in the space which its bed occupies, it does not 

 nourish. It can contribute nothing directly to the 

 nutrition of the fish. It can only do so through 

 creatures interspersed in the cycle of nutrition, be- 

 ginning with those which are at the lowest point, and 

 hold the first position. They alone count. And if we 

 think of restocking by means of new fry; if we try 

 to increase the regular population because we deem it 

 insufficient, we must take this cycle and its equilibrium 

 into account, with its capacity and its sitesis. We 

 must give due value to all these considerations and 

 act according to the results obtained. The analyses 

 of the plankton, as regards both quantity and quality, 

 make clear the line we should pursue, giving us, as 

 they do, the necessary preliminary indications on these 

 points. 



We have used the Lake of Geneva as an example. 

 It is a great sheet of fresh water, extensive yet not too 

 large, and it offers a norm which will help us to 

 realize what exists in other places. In its waters the 

 cycle of nutrition, with its chain of circumstances, its 

 equilibrium, its correlation, appears in a clear and 

 striking fashion; accessories and secondary considera- 

 tions taking a less important place. It unveils itself 

 here with a clearness unequalled elsewhere. 



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