220 



August-September, 1898. A temporary increase appears with 

 plankton pulses in cold months, as in December-January and 

 February, 1899. Some exceptions to these general tendencies 

 appear here as in Quiver Lake; such, for example, as that in 

 the low water of the autumn of 1897, when the great plankton 

 pulse of October-November attends an unusual wave of both 

 the albuminoid ammonia and the total organic nitrogen. 

 Temporary decrease in the former appears with the crest of 

 this plankton pulse, and again in the pulse of December, along 

 with an increase in organic nitrogen. The spring maximum of 

 April-May, 1898, comes with a rising wave of both substances, 

 whose crest coincides with the fall in the plankton. 



It is evident from the data here presented that the fluctu- 

 ations in the volume of the plankton, as determined by the 

 methods employed by us, show some intricate correlations 

 with the changes in the quantity of albuminoid ammonia and 

 organic nitrogen. The massing together of all organic matters, 

 both living and dead, indigenous and adventitious, in the de- 

 termination of these two substances, and the composite nature 

 of the plankton itself, including both the synthetic phytoplank- 

 tonts, and the analytic zooplanktonts, alike combine to conceal 

 the relationship which exists between the succession of living 

 forms in the plankton and the flux of nitrogenous matters in 

 suspension and solution therein. Furthermore, the plankton 

 is not the only assemblage of organisms concerned in this flux 

 of matter; the bottom fauna, the fishes and other aquatic ver- 

 tebrates, and aquatic fauna of the grosser sort, all share in 

 effecting the changes here manifest. 



We lack a common unit of measurement in terms of which 

 we can express the values alike of the chemical analyses and 

 of the volumetric and the statistical determinations of the 

 plankton. Precise comparisons, for example, of the changes in 

 the organic nitrogen with the cubic centimeters of plankton 

 and the number of diatoms cannot be made. The direction of 

 the changes in these several elements can, however, be noted, 



