NOVEMBEB 26, 1909] 



SCIENCE 



743 



America vast tracts of water discolored by 

 the mimite floating Alga, Trichodesmium 

 erythrccum, which is said to have given its 

 name to the Red Sea, and which Captain 

 Cook's sailors in the previous century 

 called "sea-sawdust." Many other nat- 

 i^ralists since have seen the same phe- 

 nomenon, caused both by this and by other 

 organisms. It must be of common occur- 

 rence, and is wide-spread in the oceans, and 

 it will be admitted that a quantitative net 

 hauled vertically through such a Tricho- 

 desmium bank would give entirely different 

 results from a haul taken, it might be, only 

 a mile or two away, in water under, so far 

 as can be determined, the same physical 

 conditions, but free from Trichodesmium. 



[Illustrations shown.] 



Nine nations bordering the northwest 

 seas of Europe, some seven or eight j'ears 

 ago, engaged in a joint scheme of biological 

 and hydrographical investigation, mainly 

 in the North Sea, with the declared object 

 of throwing light upon fundamental facts 

 bearing on the economic problems of the 

 fisheries. One important part of their pro- 

 gram was to test the quantity, distribution 

 and variation of the plankton by means of 

 periodic observations undertaken four times 

 in the year (February, May, Augiist and 

 November) at certain fixed points in the 

 sea. Many biologists considered that these 

 periods were too few and the chosen stations 

 too far apart to give reliable results. It is 

 possible that even the original promoters 

 of the scheme would now share that view, 

 and the opinion has recently been published 

 by the American planktologist, C. A. Ko- 

 foid — than whom no one is better entitled, 

 from his own detailed and exact work, to 

 express an authoritative verdict— -that cer- 

 tain recent observations "can but reveal 

 the futility of the plankton program of the 

 international commission for the investiga- 

 tion of the sea. The quarterly examina- 



tions of this program will, doubtless, yield 

 some facts of value, but they are truly in- 

 adequate to give any I'eliable view of the 

 amount and course of plankton production 

 in the sea."'' That is the latest pronounce- 

 ment on the subject, made by a neighbor 

 of yours to the south, who has probably 

 devoted more time and care to detailed 

 plankton studies than any one else on this 

 continent. 



[Examples were shown of very diversi- 

 fied plankton hauls from neighboring locali- 

 ties on the same date, or from the same 

 locality on adjacent days, to illustrate ir- 

 regularity in distribution.] 



It is evident from such results that before 

 we can base far-reaching generalizations 

 upon our plankton samples, a minute study 

 of the distribution of life in both marine 

 and fresh waters at very frequent intervals 

 throughout the year should be undertaken. 

 Kofoid has made such a minute study of 

 the lakes and streams of Illinois, and sim- 

 ilar intensive work is now being carried out 

 at several localities in Europe. 



Too little attention has been paid in the 

 past to the distribution of many animals 

 in swarms, some parts of the sea being 

 crowded and neighboring parts being desti- 

 tute of such forms, and this not merely 

 round coasts and in the narrow seas, but 

 also in the open ocean. For example, some 

 species of Copepoda and other small Crus- 

 tacea occur notably in dense crowds, and 

 are not universally distributed. This is 

 true also of some of the Diatoms, and also 

 of larger organisms. Many naturalists 

 have remarked upon the banks of Tncho- 

 desmium, of Medusas and Siphonophora, of 

 Salpse, of Pteropods, of peridinians and of 

 other common constituents of the plankton. 

 Cleve's classification into tricho-plankton 

 (arctic), styli-plankton (temperate) and 



' Inteniaiionale Revue der Eydrobiologie und 

 Hydrographie, Vol. I., p. 840, December, 1908. 



