196 THOUAES'S VIEWS. [BOOK ir. 



proposed a theory, which, although in many points similar to 

 one previously invented by his countryman, De la Hire, is 

 nevertheless, from the facts and illustrations brought by the 

 French philosopher to his aid, to be considered legitimately 

 as his own. The attention of Du Petit Thouars appears to 

 have been first especially called to the real origin of wood by 

 having remarked, in the Isle of France, that the branches 

 emitted by truncheons of Draca3na (with which hedges are 

 formed in that colony) root between the rind and old wood, 

 forming rays, of which the axis of the new shoot is the centre. 

 These rays surround the old stem; the lower ones at once 

 elongated greatly towards the earth, and the upper ones 

 gradually acquire the same direction ; so that at last, as they 

 become disentangled from each other, the whole of them pass 

 downwards to the soil. Reflecting upon this curious fact, 

 and upon others which I have not space to detail, he arrived 

 at this conclusion ; that it is not merely in the property of 

 increasing the species that buds agree with seeds, but that 

 they emit roots in like manner ; and that the wood and liber 

 are both formed by the downward descent of bud-roots, at 

 first nourished by the moisture of the cambium, and finally 

 embedded in the cellular tissue which is the result of the 

 organisation of that secretion. That first tendency of the 

 embryo, when it has disengaged itself from the seed, to send 

 roots downwards and a stem and leaves upwards, and to form 

 buds in the axils of the latter, is in like manner possessed by 

 the buds themselves ; so that plants increase in size by an 

 endless repetition of the same phenomenon. 



Hence a plant is formed of multitudes of buds or fixed 

 embryos, each of which has an independent life and action ; 

 by its elongation upwards forming new branches and con- 

 tinuing itself, and by its elongation downwards forming wood 

 and bark ; which are therefore, in Du Petit Thouars's opinion, 

 a mass of roots. 



This opinion would probably have been more generally 

 received, if it had not been too much mixed up with hypothe- 

 tical statements, to the reception of which there are strong 

 objections; as, for example, that mentioned in the last 

 paragraph. 



