1918] Michael : Behavior of Salpa deniocratica 283 



niit clem Namen Plankton bezeichnen. " In order that there be no 

 doubt as to the real meaning of Steur's words, consider the following 

 statement, also quoted from page 1 : " Die Planktonorganismen oder 

 Planktonten sind also grosstenteils kleine Lebenwesen, die ohne Eigen- 

 hcwegung oder iingeachtet dcrselhen hilffos im Wasscr trcihen . . . 

 und die Planktologie ist demnach die Lehre von den schwebenden 

 Wasserorganismen." Compare with these statements, the following 

 extracted from the first page of Schurig's Plankton-Praktikuni (1910) : 

 "Unter Plankton nun versteht man die Gesammtheit aller meist 

 mikroscopisch kleinen im Wasser schwebenden, 'flottierenden' Leben- 

 w^esen pflanzlicher und tierischer Natur, die dem Wogen keinem 

 Widerstand entgegenzusetzen vermogen, die einem Spielhall der 

 Wellen reprliseiitieren." 



That the extent to which this conception has guided the thinking 

 of able investigators may be more fully appreciated, the following 

 statements are quoted from Johnstone, Conditions of life in the sea 

 (1908): 



From page 56: "There are first of all those [organisms] which 

 by reason of their minute size and feeble powers of locomotion are 

 carried about passively in the sea by tides and currents. These are 

 they which are caught in the tow-nets, which Miiller called the Auf- 

 trieb, and Hensen the Plankton." Again, from page 57: "Then 

 one at times finds it difficult to say whether organisms, like the 

 medusae, which are carried about in great swarms by tides and cur- 

 rents, but which nevertheless are capable of some degree of locomotion, 

 are to be included in the plankton or in the nekton. ' ' Or again, from 

 page 65 : " Some worms may belong temporarily at least to the nekton, 

 and the large medusae, though perhaps better classed with the plank- 

 ton, do move about 'of their own accord.' " Or again, from page 67: 

 "These [pelagic fish eggs] have absolutely no powers of locomotion 

 and they are drifted about passively by tides and currents, the very 

 type of planktonic organisms. ' ' Or again, from page 143 : ' ' Plank- 

 ton organisms . . . have little powers of locomotion, eertainhj not such 

 as will enethle them to segregeite themselves, and they are drifted about 

 in the sea quite passively. ' ' Or lastly, from page 148 : ' ' Small 

 organisms, such as those of the plankton, are particles in the physical 

 sense and behave as such." Clearly, Johnstone (1908) has recognized 

 the real nature of the plankton concept; similar statements might be 

 (}uoted from nearly every page of his book. 



