36 CREATIVE EVOLUTION 



motions of a unicellular organism of an amoeba, at any 

 rate are sometimes explained mechanically. The dis 

 placements of an amoeba in a drop of water would be 

 comparable to the motion to and fro of a grain of dust 

 in a draughty room. Its mass is all the time absorbing 

 certain soluble matters contained in the surrounding 

 water, and giving back to it certain others ; these 

 continual exchanges, like those between two vessels 

 separated by a porous partition, would create an ever- 

 changing vortex around the little organism. As for 

 the temporary prolongations or pseudopodia which the 

 amoeba seems to make, they would be not so much 

 given out by it as attracted from it by a kind of 

 inhalation or suction of the surrounding medium. 1 

 In the same way we may perhaps come to explain the 

 more complex movements which the Infusorian makes 

 with its vibratory cilia, which, moreover, are probably 

 only fixed pseudopodia. 



But scientists are far from agreed on the value of 

 explanations and schemas of this sort. Chemists have 

 pointed out that even in the organic not to go 

 so far as the organized science has reconstructed 

 hitherto nothing but waste products of vital activity; 

 the peculiarly active plastic substances obstinately defy 

 synthesis. One of the most notable naturalists of our 

 time has insisted on the opposition of two orders of 

 phenomena observed in living tissues, anagenesis and 

 katagenesis. The role of the anagenetic energies is to 

 raise the inferior energies to their own level by 

 assimilating inorganic substances. They construct the 

 tissues. On the other hand, the actual functioning of 



1 Berthold, W/V iiber Protoplasmamechanik, Leipzig, 1886, p. 102. Cf. 

 the explanation proposed by Le Dantec, Thc orie nou=velle de la &amp;lt;vie, Paris, 

 1896, p. 60. 



