110 EAPHIDES PAYEES VIEWS. [BOOK i. 



stalked club-shaped bodies formed by calcareous precipitates, 

 first observed by Meyen, who called them Gwnmi-Keulen, in 

 some species of Ficus ; and which, in Ficus elastica, resemble an 

 ancient mace, studded with points, and attached to the top of 

 a cell by the handle. M. Pay en examined them in Ficus 

 bengalensis, nymphseifolia, elastica, Carica, and others; in 

 Pellitory (Parietaria officinalis), where they are very large ; in 

 Urtica nivea, Forskalea tenacissima; Nettle Trees (Celtis 

 australis, and misissipensis) ; in the leaves of the Black 

 Mulberry (Morus nigra), the Paper Mulberry (Broussonetia 

 papyrifera) ; the Hop (Humulus Lupulus) ; and Hemp 

 (Cannabis sativa), where such concretions are situated at 

 the base of the hairs. They generally occur in the upper 

 side of the leaf, beneath the epidermis ; occasionally, as in 

 the Fig Tree, in the lower side; and more rarely on both 

 sides and at the edge, as in hemp. A large leaf of Brous- 

 sonetia papyrifera contained 134,000 such concretions . Pay en 

 is of opinion that they are all contained in a membranous 

 bag. The unorganised or crystallisable insoluble substances, 

 he states, which are found in the interior of plants, are not 

 deposited accidentally, but are always produced in tissues 

 specially provided for the purpose, sometimes in the form of 

 stalked secreting organs. He even carries this opinion so far 

 as to state explicitly, that even "raphides in their various 

 attenuated forms are composed of a skin filled with oxalate 

 of lime, and developed in cells, consisting of a special 

 tissue, containing some nitrogenous substance." This view, 

 although adopted by M. M. Adrien de Jussieu and Richard, 

 appears to me to require further examination. Why may not 

 the mace-formed crystals of Ficus be caused by a drip of 

 mucus and saline matter from the apex of a cell, the stalk 

 being mucus only ? 



The cause of the presence of raphides or crystals in plants 

 is due to the action of vegetable acids, formed by the vital 

 processes of plants, upon such bases as may exist in the 

 tissues, whither they have been conveyed with the sap out of 

 the soil. Whether the production of such crystals is caused 

 by mere chemical affinity, or is a vital process, is uncertain. 



