APPENDIX D: BRANDT _ 4 _ 



which occur in the sea chiefly in the form of extremely small chlorophyll-bearing organisms. 

 The ocean in its entirety is comparable to very uniform and thickly populated pasture-land. 

 The microscopic plants (diatoms, Peridineae and flssion-algœ), which compose this pasture, 

 are distributed like the finest particles of dust through the upper water-layers, sufficiently 

 permeated by hght. It is only where the land rises above the oceanic pasture which 

 covers the greatest part of our Earth, that larger plants, such as sea-weeds, red algae, 

 green algae and sea grass, are found on the very narrow and also very defective ledge of 

 the coast. On the thickly populated pasture — of the land as of the ocean — the stock 

 of plant-life appears to be very scarce because the newly formed plant-substance is con- 

 stantly being preyed upon, yet a closer investigation shows immediately that a very 

 important amount of useful organic substance must in truth, be constructed in the course 

 of the year. 



There is but one method for determining the production of plant-substance in the 

 sea, namely, the plankton- method instituted in 1887 by V. Hens en of Kiel. This method 

 seeks to determine, as exactly as is possible in anything, the quality and the quantity of 

 the smaller plankton-organims contained in a column of water of known dimensions. To 

 ascertain the production for a region, it is necessary to make such hauls regularly once 

 a week during a year at the same places. The same has to be done at other coast- 

 places. The counting of the plankton, though it takes time, is quite indispensable, as it 

 is only by exact numerical determination of the plants on the one hand and of the 

 animals on the other, that we can estimate the production and consumption. For the 

 commonest forms of plants and animals occurring in the plankton, we must determine by 

 repeated investigation and observation, the rate of reproduction, the duration of the 

 various developmental stages under varying conditions and the total organic changes of the 

 species concerned; also for the commonest animals, the amount of food required and the 

 kind of food. All these must be determined before we can estimate the production from the 

 numerical data, obtained from a series of observations extending over at least one year. 



This is best done if, for the few dominant plant-species, we consider the quantity 

 taken in the first haul as capital, the reproduction as interest, and then from previous 

 knowledge of the rate of reproduction, calculate the year's production from the interest. 

 After one more year the capital is again almost as small as at the beginning. The interest 

 has all been consumed. From the quantity and species of the animals, as well as from 

 their ascertained requirements in the way of food, we can prove catch by catch, if the 

 consumption has been as great in reality as the calculation has made it. 



The production of plant-substance in the sea may then be compared with that on 

 land by arranging the chemical composition, as to quality and quantity, along parallel lines. 

 We may determine how much organic substance in general, and in particular how much 

 albumen, fat and carbohydrates, are formed per unit of surface during the course of the 

 year, on the one hand for land e. g. a pasture, on the other hand, for water. The two 

 more closely studied, main groups of plankton-flora, the Peridineae and the diatoms, are 

 very nearly related in composition to the best forage, and in autumn the plankton of Kiel 

 Bay has in general almost the same composition as pasture '. 



' K. Brandt, Beiträge zur Kenntnis der chemischen Zusammensetzung des Planktons. (Wiss. Meeres- 

 untersuch. iU. Kiel 189S). 



