634 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



minatioii, lie must eouut all the potatoes, kernels of giaiu, grapes, 

 elienies, etc., and not onlj' that, lie 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 i)oint of view, belong to the ''total 

 production" of the ground. And what would be gained b^- all these 

 immense countings? Just as little as with the "desolate figures" in 

 Heusen's long numerical protocols.* 



VOLTTME 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 simjilest way by determination of the volume and 

 "weight of each planktonic catch. Hensen himself luiturally first trod' 

 this nearest way; but he thinks that it is not accurate enough and 

 encounters difficulties (9, p. 15). In his opinion, "an accurate analysis 

 of the i)lankton, 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 ])lanktonic catch is furnished ; 

 finally that the counting of one catch is of highest value as a single 

 i'actor of a great computation, which is made from thousands of dif- 

 ferent factors. 



The only thorough method of determining the yield, in ])lanktology 

 as in economy, is the determination of the useful substance according 

 to mass and weight and subsequent chemical analj^sis. In fact, the 

 determination of the planktonic volume, as of the weight, just as the 

 qualitative and (luantitative chemical analysis of the i>lankton, is pos- 

 sible up to a certain degree. The difficulties are less than TTeusen 

 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 Daiuiida^ task of many years. 



"While Hensen is going OA'er the counting of the single constituent parts of the 

 ])lanl<ton, lui calls special attention to the fact "that in spite of the apparently" 

 desolate figur(^s, in almost every single case certain results of general interest have 

 come out, though the opportunity is not otlered to show them in a eouiparison. 



