ELEMENT AEY STBXJCTTJEE. 



33 



The raphides occur either singly in the cells in which tliey 

 are found, as in the inner bark of the Locust-tree {fig. 60) ; or 

 far more commonly there are a number of crystals in the same 

 cell, in which case they are usually arranged in one of two ways, 

 that is — either placed side by side as in the stem of Rumex {Jig. 

 62) ; or in groups radiating from a common point, and assuming 



Fig. 60. 







Fig. 60. Raphides in the cells of the inner bark of the Locust tree. After 



Gray. Fig.Qi. Couglomerate rapliides r,f the Beet Fig. 62. Acicu- 



lar raphides. Two cells contain raphides, and three of them chlorophyll. 



a clustered or conglomerate appearance, as in the cells of the 

 stem of the common Beet {Jig. 61). The former are usually 

 termed aci cuJar raphides, and the latter condome mte raphides . 

 In some'interestmg researches into the nature of raphides 

 which have been made of late years by Mr. GruUiver he has 

 distiuguished the acicular crystals, which he has called trii e^ 

 raphides, from those which occur either singly {Jig. 60), or in 

 more or less globular or conglomerate masses {Jig. 61), which he 

 has termed Sp hara^ liides. He believes that the presence or 

 absence of thdformer or true raphides, and then* comparative 

 abundance, afford characters by which the species of certain 

 orders may be distinguished at once from the allied species 

 of neighbouring orders. He has instanced the plants of the 

 Onagracege, especially, as being in this way readily distinguished 

 from the plants of allied orders. Mr. Grulliver speaks vprv 

 strongly upon this point as follows : — ' No other single diagnosis 

 for the orders in question is so simple, fundamental, and uni- 

 versal as this ; and the orders to which it applies should be 

 named raphis -hearing or raphid>ft7-ous.' Besides O.iagracese, 

 Dioscoreaceas, Araceae, and Asparagacese, are spoken of as truly 

 raphidiferous orders. 

 I With regard to Sphferaphides, Gulliver believes that there are 

 1 few, if any, orders among Phanerogamous plants in which they 

 \do not exist; hence it is questionable how far their distribution 



