102 UPWAED GROAVTH OP THE HEAD, AND pt. n. 



downward. The experiment, too, is made on the tap- 

 root and first gemmule of the seedhng, the cellular 

 structure of which I beheve in each case to differ from 

 that of all other parts of plants. 



But looking on the experiment simply as regarding 

 the vertical growth of the tap-root and gemmule of the 

 seedling, or of any vertical growth of a plant, if we are 

 to believe that this vertical growth is caused by gravity, 

 it would be a case of credo quia impossibile. For to 

 say that the sap or the new shoot — that either of these, 

 the heavier, should be caused to ascend through the 

 air, the lighter, by its weight, is as flat a contradiction 

 in terms as to say that light is caused by darkness ; 

 what Gellius said of the resurrection of the Palm-tree 

 may be said of the ascent or re-ascent of any tree, 

 adversus pondera resurgit. 



It is, indeed, the part of a thorough philosopher 

 not to wonder at anything. Those who have no pre- 

 tence to that character must wonder at everything ; and, 

 among others, at the attractive force of gravity. Why 

 a stone when dropped from the hand in the air should 

 fall towards the centre of the earth is, of itself, a most 

 unaccountably marvellous fact But this is in unison 

 with our universal, everyday experience ; and the 

 philosophic may not, and the unphilosophic do not, 

 wonder at it. But how infinitely more unaccountably 

 marvellous would it be if, owing to the same force — 

 gravity —one half of the stone were to fall towards the 

 centre of the earth, and the other half were to fly off in 



