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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
estimates in dealing with planktonic studies as giving definite data for larger compari- 
sons to be gained by such lines of research. In many respects the classing together 
of several species of genera of organisms under one typical group is misleading ; for 
instance, in the Peridinium family, heretofore platted and tabulated, there is a marked 
separation between genera such as Ceratium, which is closely limited to surface, and 
those extending more evenly down to the bottom samples, such as Glenodinium and 
Gymnodinium forms; other instances of this kind are noticeable, even in the shallow 
waters here investigated. The grouping together of allied organisms, therefore, or 
adding into totals, may lead to some more general results, but the finer analysis of the 
distribution of each species individually lays the foundation. 
Of course numerical estimates of a Plankton may always be subject to Professor 
Hseckel’s criticism, when he compares it to a farmer’s estimating the yield of hay or 
grain by counting the number of blades of grass or kernels of grain, etc. But a 
numerical estimate of the constituents of the water expressed in terms “per liter” 
will certainly give as valid a basis for comparison of the same body of water under 
different conditions, and of different bodies of water also, as any other way, and will 
be a much more accurate test, I believe, than any volumetric results or data expressed 
in weight of material in suspension. For in these last cases the greatest disturbance 
would be caused by the presence of the organic dfibris, which is often most abundant 
where the real living material secured is at a minimum. The volume of filtrate secured 
from a given sample of water is no guaranty whatever of the actual bulk of living 
organisms contained therein. And I believe that with an efficient apparatus a 
numerical estimate of each class would show many constant interrelations; but 
planktonic distribution is so very variable that statements about one locality would 
not necessarily apply to other bodies of littoral waters, however alike the seeming 
conditions of environments might be. 
It is in the hope that studies carried on in this manner may contribute to a wider 
understanding of the resources of ocean water, not only from a purely economic 
standpoint — valuable as that might be — but for the sake of the biology of the 
organisms themselves, that this paper is here offered. The author sincerely regrets 
that at present he is without the opportunities of giving the observations here recorded 
their full treatment, but ventures to present the plan of the work through the means 
offered by the United States Fish Commission, as some token of the appreciation he 
feels for the liberal encouragement and help always extended to biological work by its 
present administration. My thanks are also due to my friend Mr. hi. R. Harrington 
for the fidelity shown by him when in charge of the apparatus as these collections 
were taken; and also to all the officers of the Fish Hawk for their willing cooperation 
in every detail. The plan of the lines of sections of the survey was developed by the 
Commissioner of Fish and Fisheries, Marshall McDonald, and every hope is felt that 
this or other work of its kind may tend toward the solution of some of the ends desired 
by him. 
Williams College, 
Williams to wn : Massachusetts , December 33, 1894. 
