VEGETATION OF SEEDS. , 411 



subsequent growth receded nearly at right angles from its axis. 

 The gerraens, on the contrary, took the opposite direction, and 

 in a few days their points all met in the centre of the wheel. 

 Three of these plants were sufiered to remain on the wheel, and 

 ■were secured to its spokes to prevent their being shaken off by 

 its motion. The stems of these plants soon extended beyond 

 the centre of the wheel : but the same cause which first occa- 

 sioned them to approach its Rxis, still operating, their points 

 returned and met agarn at its centre. 



The motion of the wheel being in this experiment vertical, Eepetition of 

 the radicle and gerraen of every seed occupied, during a m.inute „,]th an*lirfii- 

 portion of time in each revolution, precisely the same position zontal wheel. 

 they would have assumed had the seeds vegetated at rest ; and 

 as gravitation -4nd centrifugal force also acted in lines parallel 

 with the vertical motion and surface of the wheel, I conceived 

 that some slight objfictions might be urged against the conclu- 

 sions I felt inclined to draw. I therefore added to the machi- 

 nery I have described, another wheel, which moved horizontally 

 •over the vertical wheels ; and to this, by means of multiplying 

 wheels of different powers, I was enabled to give many degrees. 

 of velocity. Round the circumference of the horizontal wheel, 

 whose diameter was also elo'en ir.cl'o?, seeds of the bean were 

 bound as in the experiment which I have already described ; 

 and it was then made to perform 250 revolutions in a minute. 

 By the rapid motion of the water-wheel, much water was thrown 

 upwards on the horizontal wheel, part of which supplied the 

 seeds upon it with moisture, and the remainder was dispersed, 

 in a light and constant shower, over the seeds in the vertical • . 



xvheel, and on others placed to vegetate at rest in different 

 parts of the box. 



Every seed on the horizonttil wheel, though moving with The radicles 

 great rapidity, necessarily retained the same position relative °y^^^|?,"^"f^ 

 to the attraction of the earth ; ^nd therefore the operation of downwards, 

 gravitation could not be suspended, thought it might be coun- „" '^li^^'^^' j 

 teracted, in a very considerable degree, by centrifugal force: inwards and 

 and the difference, I had anticipated, between the effects of "P^^^^'^'^^'^^g'^ 

 rapid vertical and horizontal motion, soon became sufficiently swifter tlie mo 

 obvious: the radicles pointed downwards about 10 degrees 

 below, and the germens as many degrees above, the horizontal 

 line of the wheels' motion; centrifugal force having made both 

 Ggg2 to 



