Consciousness in Plants. 327 



some influence from the tip. As with a horizontally extended 

 radicle, whose tip has been cut off or destroyed, the part 

 which should bend most remains motionless for many days 

 or hours, even though exposed at right angles to the full 

 influence of gravity, we cannot do otherwise than conclude 

 that the tip alone is sensitive to this power, and transmits 

 some stimulus to the neighboring parts, thereby causing 

 them to bend. Direct evidence of such transmission has 

 t>een obtained. When a radicle was left extended horizon- 

 tally for an hour or an hour and a half, by which time the 

 supposed influence will have travelled some distance from the 

 tip, and the tip was then cut off, the radicle subsequently 

 became bent, although it was placed in a perpendicular posi- 

 tion. Terminal portions of several radicles thus treated con- 

 tinued for some time to grow in the direction of their newly- 

 acquired curvature, for being destitute of tips they were no 

 longer acted upon by the power of gravity. New vegetative 

 points, however, appeared, and being acted on by this influ- 

 ence coursed themselves perpendicularly downward as was 

 their custom. 



Investigation having shown that it is the tip of the radicle 

 that is sensitive to geotropism in the members of such 

 distinct families as the Leguminosae, Malvaceae, Cucurbitaceae 

 and Gramineae, which may be represented by the Clover, 

 Mallow, Gourd and Rye, we may justly infer that this char- 

 acter is common to the roots of most seedling-plants. 

 Whilst a root is penetrating the ground, the tip must take 

 the incipient step, as it has to determine the direction of the 

 entire root. When, however, it is deflected by any subter- 

 ranean obstacle, it is essential that a considerable length of 

 the root should be able to bend, particularly as the tip itself 

 grows slowly and bends but little, so that the proper down- 

 ward course should be recovered. Immaterial as it would 

 seem whether the entire growing part should be so sensitive 

 to geotropism as to effect this movement, or that it should 

 ,be brought about by an influence transmitted exclusively 



