AND IRRITABILITY OF SENSITIVE PLANTS 219- 



are 40 microns in diameter, and lie in very large cells. In shape the 

 crystals might be described as being intermediate between conglomer- 

 ates and quadrangular prisms. The same type is represented for 

 0. Ortgiesi (Plate LXIV, Fig. 21). 



Oxalis violacea 



This specimen was compared with Oxalis stricta in its nyctitropic 

 movements and the crystal relation. The movement of the leaflets 

 in night sleep is exactly like that of 0. stricta. 



The crystals scattered throughout the leaflet tissue are more nu- 

 merous than in O. stricta and are more varied in shape. Some of the 

 crystals are long and narrow, 38 microns long and 8.5 microns wide. 



Oxalis corniculata 



In this, another very common native species, the crystals in the 

 leaflets are more numerous and more regular in shape than in either 

 of the two species described. Most of them are prisms, or tetrahedra 

 fewer are of the conglomerate type. The crystal relation approaches 

 very closely that of the next species. 



Oxalis floribunda 



This introduced species is native to the mountainous regions of 

 Chili. The three obcordate leaflets of each leaf show nyctitropic 

 movement (Plate LXII, Fig. 14-15). The leaflets are very feebly sensi- 

 tive to mechanical stimuli. 



The crystals are numerous, vary in shape but are mostly prismatic, 

 and are scattered through the mesophyll tissue (Plate LXIV, Fig. 23). 

 A few of. the crystals are elongated with a partition line across the 

 middle, and in general structure resemble the styloid-like crystals 

 described for the Leguminosae. 



Oxalis Ortgiesi 



This is another South American species, being indigenous to Peru. 

 The leaflets exhibit night sleep. 



The leaflets also respond to mechanical stimuli, but show slow,, 

 rather sluggish movement. 



The type of crystal present in the leaflets is similar to that of O. 

 floribunda. In the petioles and stem large crystals are found, which 

 in shape approach a prismatic form. These are scattered through the- 

 cortex but more abundantly near the bundles (Plate LXIV, Fig 21)_ 



