493 



mer and in fall, except when occasional floods would sweep it clean 

 for a time; but since the drainage canal was opened its character is 

 completely changed, and there is now but little vegetable growth to 

 be seen in it at any time of the year. It is also, of course, now con- 

 siderably larger and much more freely connected with the river than 

 before, and the lowlands separating it from the stream are much 

 longer under water. 



Plankton of Quiver Lake, 1895-99 and 1909-10 

 Cubic Centimeters to the Cubic Meter 



Averages for March, April, and May: 

 1895-'96 to l897-'98 5.50 

 1909- '10 16.15 



Consistently with these facts its plankton content per cubic meter 

 is very much greater than formerly, in whatever way the ratios may 

 be figured. Its average for the year 1909-10 is 6.13 centimeters per 

 cubic meter, while the highest average of any one of the three earlier 

 years was 2.03, and the general average for the three years was 1.93. 

 The present yield is thus more than live times that of the former 

 period. If we take into account the spring months only (March, 

 April, and May), the average yield for the three earlier years was 

 5.5 centimeters, and for 1909-10 it is 16.15 — virtually a threefold 

 increase at this most important season. 



River and Lakes Compared 



That a great change has been produced in the relative produc- 

 tivity of the river and the lakes is evident from the following table 

 of the average yield of plankton per cubic meter of these three waters. 



