G08 KEl'OKT OF COMMISSIONED OF FISH AND FISHERIES. 



in succession as great areas as possible" (23, p. 525). In a more 

 remarkable way he adds: "Thereby has resulted the furuishing of a 

 tixed basis for a thorough <[uautitative and qualitative analysis of 

 marine organisms." According to my view such "lixed basis" was 

 obtained long ago, particularly by the widely extended investigations 

 of the Challenger expedition (from January, 1873, to May, 187(5), litted 

 out with all appliances. This embraced a period of forty months, and 

 included "the whole expanse of the ocean." Their experience ought, 

 to lay claim* to J nuch greater value than that of the National, whose 

 voyage of three mouths took in only a part of the Atlantic, and was in 

 addition trammeled by bad weather, a(;cidents to the ship, early loss of 

 the large vertical nets, and other misfortunes in the carrying out of their 

 plans. It is hardly conceivable how an " exact investigator," from so 

 incomplete and fragmentary experience, can derive the " fixed basis" 

 for new and far-reaching views, which stand in remarkable contradic- 

 tion to all previous experience. 



It would here lead too far, if, from the numerous old and new narra- 

 tives of voyages, I should collect the observations of seafarers upon 

 the remarkable inequality of the sea population, thedifl'erent fauna and 

 lioraof the regions of currents, the alternation of immense swimming 

 swarms of animals and almost uninhabited areas of sea. It is sufficient 

 to ])oint out the two works in which the most extensive and thorough 

 knowledge up to this time is collected, the " Narrative of the Cruise of 

 H. M. S. ChaUenger,^^ edited by John Murray (6), and the " Collezioni 

 della E. Corvetta Vettor PisanP^ (8), published by Chierchia. Since the 

 general chorological and cecological results in these two principal works 

 agree fully with my own views gained from thirty years' experience, I 

 pass immediately to a general exposition of these latter, reserving their 

 proof for a later special work. 



A. — POLYMIXIC AND MONOTONIC PLANKTON. 



The constitution of the planldon of swimniing plants and animals of 

 different classes is exceedingly manifold. In this regard I distinguish 

 first two principal forms, polymixic and monotonic plankton.* 



The "mixed tow-atnfii {Auftrieb), or the polymixic planlcton,^'' is com- 

 posed of organisms of difierent species and classes in such a way that 

 no one form or group of forms composes more than the one-half of the 

 whole volume. The " simple tow-stuff, on the other hand, or the monotonic 

 plankton,''^ shows a very homogeneous composition, while a single group 

 of organisms, a single species or a single genus, or even a single family 

 or order, forms very predominantly the chief mass of the capture, at 

 least the greater part of the entire volume of the plankton, often two- 

 thirds or three-fourths of it, sometimes even more. Under this mon- 

 otonic i)lankton one may again distinguish prevalent planldon, when 

 the predominant group forms up to three-fourths of the total volume, 



* lloXvfiiKToz = much mixed, complex; fiovurovug = of a siuglo form, simple. 



