Radicle and Germen of Seeds, 1-23 



gated germen takes a precisely opposite direction ; and it 

 has been proved by Du Hamel * that if a seed, during its 

 germination, be frequently inverted, the points both of the 

 radicle and germen will return to the first direction. Some 

 naturalists have supposed these, opposite effects to be pro- 

 duced by gravitation j and it is not difficult to conceive that 

 the same agent, by operating on bodies so differently organ- 

 ized as the radicle and germen of plants are, may occasion 

 the one to descend and the other to ascend. 



The hypothesis of these naturalists does not, however, 

 appear to have been much strengthened by any facts they 

 were able to adduce in support of it, nor much weakened 

 by the arguments of their opponents ; and therefore, as the 

 phaenomena observable during the conversion of a seed into 

 a plant are amongst the most interesting that occur in ve- 

 getation, I commenced the experiments, an account of which 

 I have now the honour to request you to lay before the Royal 

 Society. 



I conceived that if gravitation were the cause of the de- 

 scent of the radicle, and of the ascent of the germen, it 

 must act either by its immediate influence on the vegetable 

 fibres and vessels during their formation, or on the motion 

 and consequent distribution of the true sap afforded by the 

 cotyledons : and as gravitation could produce these effects 

 only whilst the seed remained at rest, and in the same posi- 

 tion relative to the attraction of the earth, I imagined that 

 its operation would become suspended by constant and rapid 

 change of the position of the germinating seed, and that it 

 might be counteracted by the agency of centrifugal force. 



Having a strong rill of water passing through my garden, 

 I constructed a small wheel similar to those used for grinding 

 corn, adapting another wheel of a different construction, and 

 formed of very slender pieces of wood, to the same axis. 

 Round the circumference of the latter, which was eleven 

 inches in diameter, numerous seeds of the garden bean, 

 which had been soaked in water to produce their greatest 

 degree of expansion, were bound, at short distances from 



* Pbyvtque iles Arbrts. 



each 



