608 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



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

 remarkable way lie adds: "Thereby has resulted the furnisliing of a 

 fixed basis for a thorough quantitative and qualitative analysis of 

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

 obtained long ago, particularly by the widely extended investigations 

 of the Challenger expedition (from January, 1873, to May, 1876), fitted 

 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 much greater value than that of .the Ifat ion al, whose 

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

 addition trammeled by bad weather, accidents 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-reachiug views, which stand in remarkable contradic- 

 tion to all previous experience. 



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

 tives of voyages, I should collect the observations of seafarers ui)on 

 the remarkable inequality of the sea population, the different fauna and 

 flora of the regions of currents, the alternation of immense swimming 

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

 to ])<)int out the two works in which the most extensive and thovougli 

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

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

 della E. Corvetta Vetfor 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 exi)osition of these latter, reserving their 

 proof for a later special work. 



A. — POLYMIXIC AND MoNOTONIC PLANKTON. 



The constitution of the planMon of swimming 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-stuff (J. w/ifr/ei), or the polymijcic planJdon,''^ is com- 

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

 no one form or group of forms comi^oses more than the one-half of the 

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

 planlton,''^ 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 cai)ture, at 

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

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

 otonic plankton one may again distinguish prevalent planlcton, when 

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



* n.o?ivniKToc = mucli mixed, complex; uovurovog = of a single form, simple. 



