xiv Uiiivrrsitij of CaUfurnia I'uhlicalioux in Zoologij [Vol. 15 



other taxonomic group) will be founded upon an unjustified assump- 

 tion. In either case, the facts to which this assumption relates must 

 be investigated; they cannot be argued out of existence or into exist- 

 ence. Science, if really scientific, must ever proceed by induction : it 

 must observe, describe, and classify all ascertainable facts before it 

 can justify any generalization involving those facts. For* deduction 

 unsupported by induction, "carries the implication that great numbers 

 of facts of nature can be explained without having been themselves 

 examined." (Ritter and Johnson, 1911, p. 432.) 



The substitution of pseudo-scientific speculation for rigorous induc- 

 tive method reaches its extreme, perhaps, in Ostwald's (1902) viscosity 

 theory of vertical migration. Basing his speculations on a literal 

 interpretation of the commonly accepted definition of plankton as 

 "die Summe der schivehenden [italics mine] Wasserorganismen, " 

 which he (p. 596) holds to be "die allgemeinste uud entsprechend 

 grobste Definition des Planktons, ' ' Ostwald develops his theory : 

 "nicht durch Zussammenfassung von Einzelthatsachen. " but "aus 

 physikalish-chemischen Voraus-setzungen und einigen sehr allegmeinen 

 Lebenseigenschaften des Planktons." He reaches the conclusion that 

 variations in viscosity of the water, induced mainly by diurnal and 

 other periodic variations in temperature, cause plankton organisms to 

 rise and fall, thus accounting for vertical migrations. 



The theory is ingenious and, like many similar ones, is provided 

 with innumerable "cubby-holes" in which the main purport of tlie 

 theory may be conveniently concealed. It would consume more space 

 than this paper permits to point out all its fundamental weaknesses. 

 This much, however, must be said: the assumption upon which the 

 theory rests is absurd, if literally interpreted, for organisms are not 

 corks, and the most characteristic quality of an organism consists in its 

 ability to live — not in its ability to float or remain in suspension. 

 This tendency, so frequently displayed by biologists, to eliminate the 

 organism from consideration and substitute physical and chemical 

 processes for its activities, could not be scientifically justified even if 

 that organism had been manufactured of physical mixtures and 

 chemical compounds. It is precisely such substitutions that cliar- 

 acterize Otswald's theory. 



Even if variations in viscosity were the main causes of vertical 

 migration, observation demonstrates specificity in their effects: Smjitta 

 bipunctata occurs on the surface in larger numbers between 6 and 

 8 A.M. than at any other time between midnight and noon; f'alaiius 



