CA\AniA\ risiiiiiniis h\i'i:i)i i lox, i'ji'i-Ij xxv 



idea of a vertical haul were calculated to obscure the true nature of the proposition. 

 The conception of vertical hauls through the whole column of sea water, under one 

 S(iuare meter of surface, is undoubtedly derived from the simpler process of soil valu- 

 ation on land, but the knowledge gained as to the circulation of sea water, wirth its 

 surface, intermediate, and bottom currents, and the highb' fluctuating velocity of the 

 same, militates ver\- strongly against the acceptance of the vertical haul as a univer- 

 sal means of estimntimg quantitatively the production of floating organisms in a given 

 area. 



For the present, then, as long as we still lack a clear and indisputal)lc analysis of 

 the great group of problems actually invoh'ed by the questions raised, and have yet to 

 find satisfactory methods of reseax'ch for approaching the same, it would surely seem 

 far better to content ourseh^es with studying the geographical ((jualitative and quan- 

 titative) occurrence of cer'tain definite forms, applying in eacli particular case the 

 methods best suited thereto. This view has previously been advanced by the present 

 writer ^ and by Prof. H. H. Gran. "We pointed out .that a quantitative estimate of the 

 plankton in a water layer should at any rate be based upon a combination of samples 

 drawn from horizontal layers which must themselves be ylefined as closely as possible, 

 and their i^hysical and chemical conditions investigated at the same time. 

 In the case of the animal forms, several methods have 'been tried in connection with 

 such horizontal liauls. .From time to time, there have been consti-ucted more or less 

 adequate plankton nets, which could be opened and closed at certain depths, and indi- 

 cate what water they had fished, but the methods hitherto employed can hardly be said 

 to fulfil the claims of absolute accuracy in these respects. My own personal view has 

 always been, that it is unjustifiable to attempt a task which the methods of work 

 available do not suffice to accomplish, and that it is therefore better to recognize 

 the restrictions inaposed by the fact, and aim advisedly at results which shall be 

 approximately valid for certain selected forms. On the Michael Sars expedition in 

 1910, 1 found it most practical, and therefore most effective, in the case of the fishes, 

 to tow nets through the water at different depths, and then endeavour to ascertain the 

 catch made at a given depth by statistic treatment of the yield. (Vide "Depths of the 

 Ocean," pp. 615-617.) 



Only in the case of the vegetable plankton have we an altogether satisfactory 

 method of work, viz., that of H. H. Gran. Professor Gr'an was able to show, that by 

 preserving water samples (with Flemming's liquid) and subsequently centrifuging 

 them, we can obtain material sufficient for quantitative determination of the entire 

 vegetable plankton in the sample. Gran has by this means, as we know, succeeded in 

 obtaining the first real view of the true plant production of the sea,- his experiments 

 being carried out in European waters (the Skagerak) which in so many respects 

 resemble the Canadian. At most of our stations, plankton samples were collected 

 according to Professor Gran's method, and the material is dealt with by Gran in his 

 paper here given (p. 489.) 



, The paper in question throws light upon some extremely important sides of the 

 natural history of plankton. As will be apparent from the work itself, the Canadian 

 plankton reveals marked resemblances to that of the European waters. It differs, how- 

 ever, in the common occurrence of typical arctic forms, corresponding of course, to the 

 very low temperatures prevailing in the gulf of St. Lawrence during winter in all the 

 upper water layers, and in summer throughout the great intermediate layers. A point 

 of great importance for all conditions of growth in the Canadian waters is the fact 

 demonstrated by Gran, that the development takes place much later in the year there 

 than in the waters of northern Europe. This naturally agrees with the fact that the 

 gulf of St. Lawrence was full of ice until nearly the middle of May — and it is interest- 

 ing to note, in this respect, that while the growth of the herring in the far more north- 



1 See, for instance, "Depths of the Ocean," pp. 771-785. 



2 H. H. Gran. The Plankton Production of the North European Waters in the spring, 1912. 

 Bulletin Planktonique pour I'annfee 1912 public par le bureau du Conseil Permanent Inter- 

 national pour I'exploration de la mer. Copenhague, 1915. 



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