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 zoéplanktonts, 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, 
