UBRARY 



fl, O. state College 



PREFACE 



" Little do ye know your own blessedness ; for to travel hopefully is a better thing than 

 to arrive, and the true success is to labour." R. L. Stevenson, Essay on '■^El Dorado.'" 



In this passage Stevenson enunciates a truth that applies with singular 

 force to those who enter on morphological enquiry. To travel hopefully is 

 the chosen pursuit of all whio study large groups of organisms with a view 

 to reducing them to order, so as to throw light on their origin and evolution. 

 In such quests no one need expect under present conditions to arrive at the 

 final destination of complete and assured knowledge. If any one should 

 indulge this hope his disappointment is certain. Even if he did so arrive, 

 and found himself able fully to demonstrate the whole truth, how greatly 

 would the quest lose in its interest. It is in the pursuit of his " El Dorado " 

 of evolutionary history, not in the arrival there, that the true blessedness of 

 the morphologist lies. It behoves then those who travel on this journey 

 not to hurry unduly, but to consider with critical care the manner of their 

 journeying, rather than to seek short cuts to an elusive goal. 



Bacon in the Novum Organiiin laid it down that there are only two ways 

 in which knowledge can be sought : viz. by anticipations of Nature, and by 

 interpretations of Nature. In the former method men pass at once from 

 particulars to the highest generalities, and thence deduce all intermediate 

 propositions. In the latter they rise by gradual induction, and successively 

 from particulars to axioms of the lowest generality, then to intermediate 

 axioms, and so to the highest. He asserts that this is the true way. 

 There will be good ground for hope, he says, when any one can be found 

 content to begin at the beginning, and to apply himself to " experience and 

 particulars." 



It will depend in some degree upon the data available for study of the 

 question in hand which of these two methods shall be used. Where the facts 

 are few and disconnected the former may appear preferable. But the fewer 

 the facts the less reliable will be the conclusions: till at last the results arrived 

 at by the deductive method may be little better than speculations, liable to 

 be modified or refuted by any positive discovery. The deductive study of 

 evolution is in fact the refuge of those who, finding themselves destitute of 

 the necessary data, are still determined to arrive at some conclusion. They 

 accordingly use their imagination to make up the deficiency. The inductive 

 method will be preferred in any case where the facts are many and cognate, 

 so that they can be arranged in continuous sequences. It is true that the 

 data may be read in divers ways, according as greater or less weight is 

 assigned to one detail or to another. But against this criticism it may be 



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