34 



ORGANOGRAPHY. 



might be rendered available as a means of distinguishing plants 

 from one another. Their presence, however, he finds universal in 

 every species of the orders Caryophyllacese, Greraniacese, Parony- 

 chiacese, Lythracese, Saxifragracese, and Urticacese; hence he 

 regards the presence of Sphseraphides as especially characteristic 

 of these orders. 



In the common Arum and some other Aracese, the cells which 

 contain the raphides are filled with a thickened sap, so that 

 when they are moistened with water, endosraose takes place, by 

 which they are distended and caused ultimately to burst and 

 discharge their crystals from an orifice at each end {fig. 63). 

 Such cells have been called Biforines. 



In many plants belonging to the families of the Urticacese, 

 Moracese, and Acanthacese, there may be frequently observed 



Fig. 63. 



Fig. 64. 



Fig. 65. 



Jfifir. 63. Raphides of an Anim heing discharged under the influence of 



water. Fig. 64. Cystoiithe, from Pnrietnria officinalis. After Henf rey. 



Fig. 65. Cystoiithe, from the leaf of Ficus elastica. After Henfrey. 



situated generally just beneath the surfaces of the leaves, or 



sometimes more, deeply, peculiar crystalline structures, to which 



the name of Cystolithes has been applied by Weddell. These 



consist of an enlarged cell containing commonly a globular or 



club-shaped mass of crystals {figs. 64 and Qi))^ suspended from 



the top by a kind of stalk formed of cellulose, upon which the 



crystals are deposited as upon a nucleus. Crystals are also 



found of other shapes besides the globular and clavate in these 



Cystolithes. All crystals found in these structures consist of 



carbonate of lime. 



t The ordinary acicular or true raphides of Gulliver, and con- 



I glomerate raphides (Sphseraphides), appear to be simple chemical 



jf combinations of the organic and inorganic acids and bases (com- 



1 monly lime) which are contained in the fluids of the plant. Such 



crystals, therefore, vary in composition, those of most frequent 



occurrence consisting of oxalate of lime, as in Rhubarb root. 



,' The acicular raphides appear to vary in composition in different 



plants, for while some observers have described them as com- 



