SOME PROBLEMS OF THE SEA. 17 



to serious objections, the most fundamental of which, to 

 my mind, is the obvious irregularity in the distribution 

 of the plankton — horizontally, vertically, and chrono- 

 logically — an irregularity which must vitiate any calcula- 

 tions based upon comparatively few and distant samples. 

 I am distinctly of opinion that marine biologists ought 

 to concentrate their efforts upon the intensive study of 

 small areas before trying to estimate the contents of an 

 ocean or even of a fishery district. Until we understand 

 more fully the plankton of Port Erin, of Plymouth 

 Sound, of the Firth of Forth, or of the Bay of Kiel, it is 

 premature to attempt the North Sea or the Atlantic Ocean. 

 The conclusions to which I have come do not lead me to 

 be discouraged as to the ultimate success of scientific 

 methods in solving what may be called world-wide 

 problems, but they suggest that it might be wise to secure 

 by detailed local work a firm foundation upon which to 

 build, and to ascertain more accurately the representative 

 value of our samples before we base conclusions upon 

 them. 



I do not doubt that in limited, circumscribed areas 

 of water, in the case of organisms that reproduce with 

 great rapidity, the plankton becomes more uniformly 

 distributed, and a comparatively small number of samples 

 may then be fairly representative of the whole. That is 

 probably more or less the case with fresh-water lakes ; 

 and I have noticed it in Port Erin Bay in the case of 

 diatoms. In spring, and again in autumn, when suitable 

 weather occurs, as it did this year in the last week of 

 September, the diatoms may increase enormously, and 

 under such circumstances they seem to be very evenly 

 spread over all parts and to pervade the water at all 

 depths; but that is emphatically not the case with the 

 Copepoda and other constituents of the plankton. 



B 



