242 EVOLUTION 



work itself out just as fully and freshly as 

 did the selectionist game of thought: if not, 

 it remains useless to argue for it. The eye 

 sees only what it brings the means of seeing. 



Re-interpretation of the Animal King- 

 dom. — Instead then of opening new^ botanical 

 sections, of which each would really require 

 a chapter, sometimes a whole volume, now 

 dealing with the interpretations of flowers 

 and of fruits, and again with the great pecu- 

 liarities of habit — evergreens, thorny plants, 

 climbers and so on, let us rather ask: Can 

 any such physiological interpretations be 

 applied to a survey of the animal kingdom? 

 Its problems are obviously far more intricate 

 and varied: yet the result is scarcely less 

 definite or comprehensive. In the outline 

 of our restatement of the cell-theory as a 

 "theory of the cell cycle" (Chapter III) we 

 have already interpreted such main forms of 

 Protozoa as the rhizopods, the gregarines, the 

 infusors, not from without, as the empirically 

 selected products of spontaneous variations 

 among indefinite possibilities, but from with- 

 in, as simply the preponderatingly amoeboid, 

 resting, and motile phases of the cell-cycle, 

 three forms determined by the properties of 

 protoplasm itself. 



This conception of life-histories, as physio- 

 logical and not merely structural, ration- 



