566 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



which lie names "planktology"; the distinctions which he points out 

 between the varied constituents and distribution of the plankton; and 

 finally his extremely valuable suggestions for further work in the field 

 which he so justly terms "a wonder-land." 



In the translation .the liberty of omitting a few personal references 

 was taken, for the reason that we in this country know very little of 

 the facts which have called them forth. 



In the case of several German words it has been found necessary for 

 the sake of clearness to use a circumlocution. For instance, I can recall 

 no English equivalent for '■' Sioffwechsel des Meeres,^'' which would con- 

 vey its meaning in a single word. The " cycle of matter in the sea," 

 i. e., the change of inorganic matter into vegetable and animal organic 

 matter, and this finally again into inorganic matter, seemed the best 

 rendering, though even this does not include all which the German term 

 implies. 



I.— HISTORICAL EXPLANATIONS. 



For the great progress made in the last half century in our knowledge 

 of organic life, we are indebted — next to the theory of development — in 

 a great measure to the investigation of the so-called " pelagic animal 

 world." These wonderful organisms, which live and swim at the surface 

 of the sea and at various depths, have long aroused the interest of sea 

 farer and naturalist, by the wealth of the manifold and strange forms, 

 as well as by the astonishing number of individuals — these have been 

 referred to in many old as well as in recent narratives. A considerable 

 number of these, especially of the larger and more remarkable forms, 

 were described and figured in the last, or in the first half of the present, 

 century. The new and comprehensive investigation of the "pelagic 

 world" began in the fifth decade of our century, and is therefore not 

 yet 50 years old. 



Into this, as into so many other regions of biology, the great 

 Johannes Miiller, of Berlin, equally distinguished in the realms of 

 morphology and physiology, entered as a pioneer. He was the first 

 who systematically and with great results carried on the "pelagic 

 fishery by means of a fine net." In the autunui of 1845, at Helgoland, 

 he began his celebrated investigations upon the development of 

 echinoderms, and obtained the small pelagic larvre of the echinoderms, 

 and other small pelagic animals living with them, as sagitta, worm 

 larvje, etc., at first by "microscopical examination of the sea water, 

 which was brought in" (1). This wearisome and thankless method was 

 soon displaced by the successful use of the "fine pelagic net." In the 

 treatise "on the general plan in the development of the echinoderms," 



Note. — Citations inclosed in parentheses which occur in the text refer to the list of 

 publications at the end of this paper (pp. 040, 641). 



