THE PLANT AS A PARENT 



937 



straight downward. Seeds wliich haw 

 been continually turned go through the 

 strangest contortions in order that they 

 may anchor themselves in the ground. 

 It might be thought that it was the desire 

 of the roots to get away from the light, 

 had it not been shown that seeds grown 

 in a box with holes in the bottom will 

 send their radicles down through the 

 openings out into the open. In doing so 

 they leave not only the darkness behind 

 them, but also the moisture in which 

 they germinated. 



It has been suggested, and with a good 

 deal of reason, that the law of gravita- 

 tion has not a little to do with this strange 

 tendency on the part of plants. Years 

 ago a president of the Royal Horticultural 

 Society, Mr. J. A. Knight, germinated 

 bean seeds on the rim of a vertical wheel, 

 which was always kept revolving. Arrange- 

 ments were also made to keep the seeds 

 in a moist condition favourable to growth. 

 It was found that the roots of the seedlings 

 now grew outwards away from the centre 

 of the wheel. From this it would appear 

 that when the action of gravitation was 

 overthrown bj^ the centrifugal force of the 



THE DANDELION IS TYPICAL OF THE 

 FLYING SEEDS. 



119 



THE SEEDS OF THE BULRUSH ARE CARRIED 

 TO GREAT DISTANCES BY THE WIND. 



It is computed that the head of the bulrush contains as 

 many as a million seeds. 



revolving wheel the little plants were 

 influenced by the new power. Thus it 

 seems to be evident that the influence of 

 gravitation in directing the course of the 

 roots of seedlings is considerable. This 

 does not by any means offer a complete 

 solution of the problem ; for whilst the 

 root goes downwards the shoot with 

 almost equal precision directs its growth 

 upwards. It must be admitted that there 

 IS something more than a mere mechanical 

 influence at work. We are indeed brought 

 face to face with one of those mysteries 

 which are as inscrutable as life itself. 

 The most that can be said is that the 

 radicle of the seedling is endowed with a 

 geotropic tendency which impels it to 

 bury itself in the earth, the tendency of 

 the shoot meanwhile being in an opposite 

 direction. As to the underlying causes 

 of the happenings we are in complete 

 ignorance. 



Whilst the radicle of the seedling must 

 always grow downwards, such is not tiie 



