CH. V] SPLIT ROOT. 141 



(164) Splitting a root. 



In some turgescent structures the erectile (compressed) 

 tissue is external, while the resisting or stretched tissue 

 is internal. In such cases the result of splitting longi- 

 tudinally must obviously be the opposite of that just 

 described : the parts will curve inwards, towards the 

 longitudinal axis, not away from it. 



Pull up a seedling bean (V.faba) with a root 3 or 4 cm. 

 long, split the apical centimeter with a scalpel, and put it 

 in lukewarm (25° — 30° C.) water. The halves will certainly 

 not curve outwards, and will after a little time show a 

 slight inward bend. The aerial roots of Aroids show the 

 same tensions. 



(165) Splitting a pidvinus. 



Take a large pulvinus of Phaseolas and cut from it an 

 axial slab as described under experiment 163. Split the 

 slab down the central strand, and put the halves in water, 

 when they will curve inwards, i.e. with the vascular tissue 

 on the concave side. 



