634 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
mination, he must count all the potatoes, kernels of grain, grapes, 
cherries, ete., and not only that, he must also count the blades of grass 
of his meadow, even every individual weed which grows among the 
grain of his field and the useful plants of his: garden; for these also, 
regarded from the physiological point of view, belong to the “total 
production” of the ground. And what would be gained by all these 
immense countings? Just as little as with the “desolate figures” in 
Hensen’s long numerical protocols. * 
VOLUME AND WEIGHT OF THE PLANKTON. 
If one actually regards the determination of the planktonic yield as a 
highly important subject, and believes that this can be solved by a 
certain number of quantitative plankton analyses, then this goal can 
be reached in the simplest way by determination of the volume and 
weight of each planktonic eatch. Hensen himself naturally first trod 
this nearest way; but he thinks that itis not accurate enough and 
encounters difficulties (9, p. 15). In his opinion, “an accurate analysis 
of the plankton, on account of the great variety of its parts, can only 
be obtained by counting; he quite forgets that such a counting of 
individuals also possesses only an approximate and relative value, 
not a complete and absolute one; farther, that from the counting of the 
different individuals no more certain measure for the economic value 
of the whole diversely constituted planktonic catch is furnished ; 
finally that the counting of one catch is of highest value as a single 
factor of a great computation, which is made from thousands of dif- 
ferent factors. 
The only thorough method of determining the yield, in planktology 
as in economy, is the determination of the useful substance according 
to mass and weight and subsequent chemical analysis. In fact, the 
determination of the planktonic volume, as of the weight, just as the 
qualitative and quantitative chemical analysis of the plankton, is pos- 
sible up to a certain degree. The difficulties are less than Hensen 
believes. It seems odd that the latter has not mentioned these two 
simplest methods in a single place in his comprehensive volume (9, p. 
15), but hastily casts them aside and replaces them with the quite use- 
less “counting of individuals,” a Danaide task of many years. 
*While Hensen is going over the counting of the single constituent parts of the 
plankton, he calls special attention to the fact ‘‘that in spite of the apparently” 
desolate figures, in almost every single case certain results of general interest have 
come out, though the opportunity is not offered to show them in a comparison. 
