34 CREATIVE EVOLUTION [chap. 



the air is extracted from an alveolus, a cone of attraction 

 is seen to form, like those about the centrosomes which 

 result in the division of the nucleus. 1 Even the external 

 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 con- 

 tinual exchanges, like those between two vessels separated 

 by a porous partition, would create an everchanging 

 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. 2 In the same way we may perhaps 

 come to explain the more complex movements which the 

 Infusorian makes with its vibratory cilia, which, more- 

 over, are probably only fixed pseudopodia. 



But scientists are far from agreed on the value of ex- 

 planations 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 



1 Rhumbler, Versuch einer mechanischen Erklarung der indirekten 

 Zell- und Kernteilung (Roux's Archiv, 1896). 



2 Berthold, Studien uber Protoplasmamechanik, Leipzig, 1886, p. 102. 

 Cf. the explanation proposed by Le Dantec, Thiorie nouvelle de la vie, 

 Paris, 1896, p. 60. 



