EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 213 



perhaps have committed, had he invoked the aid of chemistry. M. Payen, 

 however, has succeeded in determining the nature of the crystallized sub- 

 stances, their position, and the mode of their formation, not only in the 

 genus Ficus, but in other Urticacea, and in many other plants of diffe- 

 rent families. These productions are not formed simply of a crystallized 

 mineral substance, but contain besides an organic tissue which secretes 

 the mineral matter in solution, and becomes the matrix in which this 

 matter is afterwards crystallized. It is consequently evident, that the 

 apparatus must exist before the crystals are apparent. This apparatus, 

 placed in the centre of a large utricule, is composed of two parts, dis- 

 tinct in their structure and function. The one is composed of a tissue 

 in all respects similar to that surrounding it, and constitutes a cellular 

 cord, attached by its superior extremity to the inner surface of the epi- 

 dermic layers. The other part is a delicate tissue of cells, so minute 

 that they appear scarcely more than points, and so numerous, that by 

 their aggregation they form a mass of considerable size, suspended like 

 a chandelier, at the end of the cord, in the cavity of the large utricule. 

 The progress of vegetation produces no appreciable modification in the 

 cord itself ; but this is not the case with regard to the delicate tissue 

 which secretes the carbonate of lime. The vacuities of this organ, 

 become gradually filled with a solution of the salt, which soon crystal- 

 lizes ; and there are now apparent on the exterior cellular layer, the 

 minute mamillary projections, sometimes angular, which Meyen, in his 

 ignorance of the presence of the delicate cellular tissue, mistook for an 

 envelope of bare crystals, deposited on the surface of the central gummy 

 mass which he supposed to exist. The above description applies to 

 many species of the Urticacece ; but it must be remarked, that the same 

 arrangement is not found in all the plants in which crystals have been 

 observed. Those, for instance, of the Cannabis sativa and of the Brous- 

 sonetia papyrifera, are suspended from the inner wall of the utricules 

 composing the hairs of these two Urticacece. 



M. Payen has described and figured the incrustations of carbonate of 

 lime, which are met with in the stalk of Chara. He describes them as 

 lodged in a superficial cellular tissue, containing much azote, and which 

 envelopes the tubular utricules, disposed in a circular series, around the 

 great central cavities. 



The very different forms assumed by the crystals of oxalate of 

 lime, and the position which they take in a great number of stalks and 

 leaves, merit particular attention. This salt has been found in small 

 agglomerations of acicular crystals, radiating from a common centre 

 in the parenchyma, and around the nervures of the leaves of many 

 plants. It occurs in rhombic crystals of a certain size in the parenchyma, 

 of the leaves and under the epidermis of Citrus, of Limonia, and of 

 Juglans regia, and in still larger masses in the Cacti; and M. Payen 

 remarks, that there is a great analogy in the forms of crystals in the 

 more allied species, citing as examples of this, Opuntia, Echinocactus, 

 Cereus, Cactus, and Rhipsalis. 



Every phytologist has observed the minute needle-shaped crystals 

 named Raphides. They are so slender, that under a magnifying power 

 of 300 diameter, they present to the eye of the observer merely 



