Plant-Crystals. By Br. Aser Boh. 599 



A very interesting form is that of crystals which are surrounded 

 by an integument of cellulose, and fixed by this to the walls of the 

 cell (see PL VI. Figs. 1, 2, and 3). They were seen first by 

 Bosanoff (Bot. Ztg., 1865,) in Ricinus and Kerria Japonica, 

 and afterwards in many Araceae, in the fruit of Rosa (by Poulsen, 

 who named them RosanofT-crystals\ in the pith of many Malvaceae 

 (Sida, Hibiscus, Lavatera, &c) in the Rigelliria Africana, Mer- 

 c >i rial is annua, and some Celastraceae and Bhamnese. These 

 ligaments of cellulose are perforated, tubiform, and in the Malvaceae 

 they are found also in the cells which do not contain crystals, 

 but in continuation of ligaments which surround the crystal of the 

 contiguous cell (Fig. 3 bis). 



Crystals are found also in the walls of cells, in the epidermic 

 cells of many species of Sempervivum and Mesembryanthemum, and 

 in the fibres of liber of many Coniferae (Solms-Laubach and Pfitzer). 



IV. Plant-crystals as a Taxonomic Character. — Crystals are 

 not frequent in Cryptogameae and Gymnospermeae ; but in the 

 Angiospemiae they form the constant character of many families 

 and groups of plants. Gulliver has proved the constant presence 

 of crystals, and especially of raphides, in certain plants. He has 

 found raphides in many orders, of which examples occur in Vitacea3, 

 Mesembryanthemeae, some Nyctagineae, in Balsaminaceae, Onagra- 

 ceae, and Galiaceae ; and in the British flora he defines the Bal- 

 sarainaceas as Geraniales abounding in raphides, the Orchidaceae 

 as Gynandrous Endogens abounding in raphides, and Galiaceae as 

 Corollifloral Exogens abounding in raphides. Vesque * has found 

 that the presence of raphides is a constant character of Dilleniaceae. 

 We may then define Dilleniaceae as Ban ales with raphides. 



In the Lemnaceae the genus Lemna contains raphides, the 

 genus Wolfia is wanting in raphides. Vitaceae contain every form 

 of crystals in the stem, leaves, and fruit. Almost all ligneous 

 plants contain sphaeraphides in their pith and bark, and short 

 prismatic crystals in the bast-fibres and sometimes in the wood 

 (Clusia). Celastraceae and Pihamneae contain Bosanoff-crystals in 

 the pith and the bark (Fig. 3). The bark and pith of many 

 herbaceous plants (e. g. Labiatae), contain free, abounding, little 

 crystals. Many Monocotyledons contain only raphides (e. g. Orchi- 

 daceae, Narcissus, many Liliaceae, &c.) ; the Iris has long prismatic 

 crystals, Araceae raphides and sphaeraphides. (In my above- 

 mentioned work there is a list of plants which contain crystals.) 



V. As to the physiolor/ical function of crystals in plants we 

 know very little. It seems that oxalate of calcium is a useless 

 product of plants, because it is often eliminated from the plant by 

 the fall of dead leaves and old bark ; it is generally accumulated 



* Tesque, " L'Anatomie des tisstis applique'e a la classification des Plantes," 

 Nouvelles Archives du Museum d'Hist. Nat., iv. (1881). 



2 s 2 



