36 THE WHEAT CULTUEIST. 



fibre was cut through at its base, the motion of the 

 sucker was sudden and convulsive, and the contents dis- 

 charged with considerable elasticity. 



" In the roots grown naturally within the earth, the 

 circulation of the fluid contents of the suckers, when 

 observed, was slow and feeble. Those which yet re- 

 tained the granular substance withinside, were as yet 

 free from the external papillae, while those covered with 

 the viscous masses outside, were nearly empty internally. 

 But in these cases the excretion appeared but rarely to 

 have been affected by the bursting of the extremity, but 

 usually by exudation, through the membrane forming 

 the walls of the cavity, and that in a manner which 

 could scarcely be explained by endosmose alone, but by 

 some other force unknown to us, and which must be 

 included in the mysteries of vital action. 



" With regard to the effects produced by these exuda- 

 tions on the capabilities of the soil for the nutriment of 

 other plants at the same time, or in succession, there is 

 nothing to show that they possess any acid, caustic, or 

 saline properties likely to act prejudicially on other 

 roots. Whether the matter be compared to the fecal 

 excretions or to the residue left by insensible perspira- 

 tion on the skin of animals, it' can well be imagined 

 that it cannot serve for nutriment if reabsorbed by the 

 same plants, nor probably if absorbed by others until 

 decomposed ; but owing to its extreme tenuity the decom- 

 position takes place very readily ; and as recent detritus 

 of vegetable matter, its quantity is very small in com- 

 parison to that of the decayed sucker and pileorhizas, 

 and of the numerous fibres which perish from natural 

 or accidental causes. If in the relative effect of differ- 

 ent plants on the impoverishment of the soil, the radical 



