— 5 — APPENDIX D: BRANDT 



The very numerous hauls of plankton made during the German quarterly cruises, have ^''^ preiimin- 



ary work al- 



been subjected to enumeration by Dr. Ap stein, partly with Dr. Rauschen plat, in order ready carried 

 to determine exactly, the horizontal and vertical distribution of the principal plankton- °"' f»"' ">« 



(> 1 T»T 1 ^ determination 



organisms m the regions of the North Sea and Baltic, and their relation to the seasons of the actual 

 of the year. The results of the investigations for 1903 will be published this winter, production in 

 those for 1904 not before next summer. The opportunity has been utilised also, to make ^nd Baltic 

 special hauls for the investigation of the chemical composition of the plankton. A portion 

 of this new material has already been worked out by Dr. Stiehr. Further investigations 

 will also be set on foot to ascertain the structure, development, reproduction and habits, 

 of the characteristic plant and animal forms of the plankton and their relation to other 

 organisms, as well as to the outer conditions of life. Work is also being done on the 

 plankton-methods, viz. comparison of the different nets, the quantities of the smallest 

 plankton-organisms escaping through the pores of the nets, and the best method of 

 quantitative estimation of the hauls. With respect to the last. Dr. Apstein has just 

 published an essay in which he maintains the indispensability of counting the plankton 

 and the unserviceableness of mere estimates ^. 



Whilst these investigations are intended so to perfect H e n s e n ' s plankton-methods 

 that a great, coherent investigation of the true production (e. g. in the North Sea) may be 

 made in the not distant future, other preparatory work is also being done, which will 

 contribute to deepening and extending the value of the results reached by the plankton- 

 investigations. The aim of these new investigations is to learn more definitely, the general 

 conditions of production in the ocean and to determine the factors on which the produc- 

 tion depends ''. 



As the existence of animals is dependent on that of plants, so are these again Theconditions 



of production 



dependent on the general conditions of production for the amount of production. 



To gain information concerning the productivity of a region of the sea, it will probably 

 soon be sufficient to make an exact investigation of the general conditions of production, 

 which are very much simpler and more uniform in the sea than on land. For this, we 

 shall require to take into consideration, the scarce but indispensable food-stuff of plants 

 dissolved in the water, and also the intensity of light — both of which investigations have 

 been but little pursued hitherto — as obviously, the varying amount of the production in 

 the sea depends mainly on these two factors. 



This will only be possible, however, when we have made more detailed and extended 

 investigations and are better informed than al present, of the natural relations between 

 the conditions of production and the actual production. 



The plants produce just so much organic substance as is allowed by the general 

 conditions of life in the land- or water-region considered, and in fixed relation to the 

 amount of inorganic food-materials at their disposal. In this, however, they come under the 

 law of the minimum. If one of the indispensable constituents of plant-food is present in 

 very small quantities, the production is also small. The production ceases entirely if one 

 of the indispensable constituents is absent. 



Almost all marine plants, macroscopic or microscopic, take the nourishing salts not 



' C. Apstein, Die Schätzungsmethode in der Planktonforschung (Wiss. Meeresunters. Kiel). 

 ' K. Brandt, Ueber den Stoffwechsel im Meere, 1. u. ,'. Abhandl. (Wiss. Meeresu liters. IV. u. VI. 

 Kiel. 1899 und 1902). 



