CRYSTALS. 



53 



of the leaves, and detached entire ; on becoming turgid when 

 wetted, they will usually discharge their raphides one by one 

 from one or both ends of the cell until the bundle is almost 

 exhausted.^ 



186. When the ordinary' octahedral or prismatic crystals 

 are aggregated or 



combined, they 

 generally compose 

 a spherical mass. 

 Such aggrega- 

 tions are of two 

 principal types : 

 ( 1 ) those made 

 up of many small 

 crystals irregular- 

 ly grouped, and 

 usually- presenting 

 sharp points over 

 the surface, as 

 in Fig. 36 a; (2) 



those with a distinctly radiated structure (Fig. 36 1). Good 

 examples of the former are abundant in the foliage of Chenopo- 

 diaceas and the stems of Cactaceffi. Clusters belonging to the 

 latter, or stellate, t3'pe are not uncommon in Malvaceae. Both 

 forms have been termed SphcBraphides ^ and Sphere-crystals. 

 The term cystolith, sometimes improperly applied to them, 

 should be whollj- restricted to the peculiar bodies described on 

 page 40. 



187. Owing to the mechanical difficulty of isolating plant- 



1 Turpin (Annales des Sc. nat., ser. 2, tome v., 1836) described the raphldes- 

 beaving cells of Caladium, in which tliis discharge takes place, under the name 

 of Mforines. 



2 " They are most irregularly scattered through the tissues of the plant. 

 ... I have never failed to find them in a single species of the order Caryo- 

 phyllacese, Geraniaceae, Lythi'acese, Saxifragaceae, and Urticaceas, and believe 

 that few if any orders could be named in which sphseraphides do not exist as 

 part and parcel of the healthy and growing structure of the plant " (Gulliver, 

 in Annals and Magazine of Natural History, vol. xii., 1863, p. 227). 



Fig. 36. The more important forms of crystals of calcic oxalate: a, three cells from" 

 the petiole of Begoni.i maiiicata ; 6, from the leaf of Tradescantia discolor ; c and 

 d, from the leaf of Allium Cepa; e, from the inner bark of .iEsculus Hippocastamim ; 

 /, from the leaf of Cycas revoluta; g, a cell containing raphides, from the frond of 

 Lemna trisiilca; A, a single crystal from the same, more highly magnified ; i, sphjero- 

 crystal from Phallus caninus. (Kny, ) 



