IRRITABILITY. 



535 



FIG. 56 (after Gardiner). Transverse section of pulvinus of Mimosa pudica; 

 b, parenchyma of lower half; c, fibro vascular bundle; d, parenchyma of 

 upper half. 



described by Pohl in 1779. The lateral leaflets are inserted 

 by means of a relatively long pulvinus on opposite sides of 

 the main petiole just below the large terminal leaflet. The 

 leaflets move upwards and downwards, changing their position 

 sometimes by as much as 180. At the same time they twist 



FIG. 57 (after Duchartre). Leaf of Hedysarum (Desmodium] gyrans. 



