78 THE THEOKY OF EVOLUTION 



were induced by them. If the changes of form of the 

 fossils remain within the limits of those alterations 

 which we at present observe in the recent organisms, 

 or can, with great probability, deduce from them, then 

 are we certain that our explanation is correct. If they 

 extend farther, we must inquire whether an increase 

 in the intensity and the duration of that influence may 

 not explain the great scope of the deviations. The 

 certainty of our deductions certainly is decreased 

 thereby. How far the application of these principles 

 may be carried is not, however, left open to choice 

 which might be satisfied with a mere glimmer of possi- 

 bility and probability : we must act within the limits 

 set by Nature and by Science, regarding which we have 

 already said what is needful when discussing the results 

 of palseontological research. 



This truly scientific standpoint is that assumed 

 by many eminent palaeontologists, such as Neumayr, 

 Waagen, Zittel, Koken, Steinmann, Deperet, Kerner, 

 Marilaun, Keinke, and Wasmann. 



We believe, however, that in many cases, especially 

 in advanced ' reading circles/ such a standpoint is re- 

 garded as simply ' naive ' : one is accustomed there 

 to see quite other and deeper-seated questions treated 

 after a certain ' dogmatic method/ in books on evolu- 

 tional history, which commence with these purely 

 scientific problems and proceed to the most subtle 

 questions of world-wide breadth (Weltanschauung). 

 Why we do not do that, we will explain as follows. 

 In the first place, a word on the so-called ' palseonto- 



