HORSE-CHESTNUTS 



98 



It may be that the purpose and function of the mem- 

 branous coatings of the radicle and plumule and the peculiar 

 junction of the two have some connection with electrical 

 supply. Before the rupture of the inner membrane of the 

 seed in open ground growth the seed substance is positively 

 ■electrified by induction. When by reason of the rupture 

 of the inner membrane the seed substance is placed in direct 

 contact with the soil it must become negatively electrified 

 and without any provision being made to conserve a 

 difference of polarity the whole seedling would be negatively 

 ■charged ; the stomata as yet not being able to take in 

 charge from the positive air ; although the leaf buds might, 

 as a matter of possibility, obtain oxygen from the soil and 

 so establish a circuit. But it is not altogether improbable 

 that the membranes of the radicle and plumule interpose 

 as effective a resistance as did the inner membrane while 

 it was intact — until, at all events, the leaves could unfold 

 and take in air charge. In such case the electrical condition 

 would be for a time unchanged, but when the plumule 

 with its crown of leaves gained access to the air the inductive 

 process would no longer be necessary and the seed substance 

 would, so far as its electrical function is concerned, merely 

 serve to assist in collecting or in storing earth-energy. 



In the first sketch of this series 

 only the first leaves have developed 

 and the radicle is destitute of root 

 filaments ; the two being, presumably, 

 balanced. When, however, the second 

 leaves are formed further root 

 development is required to keep pace 

 with upward growth and in order 

 to preserve electrical equilibrium. 



The accompanying figure shows the 

 last example with the seed cut in 

 section : 



