CH. V] SPLIT ROOT. 129 



(164) Splitting a root. 



In some turgescent organs 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 (Faba) with a root about IJ 

 inches long, split the apical half-inch 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. 



(16-5) Splitting a pulvinus. 



Take a large pulvinus of Phaseolus and cut from it an 

 axile 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. 



D. A. 



