9.0 Dr F. Unger on the Formation of Cells in Plants. 



crystal cellules are often free, and project in the interior of 

 these cavities ; and this is especially true of the acicular crystals, 

 as M. Meyen has demonstrated in his Phytotomy ; and I have 

 also observed it in the starry like crystals of the Myriophijllum 

 splcatum. The existence of crystals seems to be connected with 

 the cells containing fecula, and such like substances, such as 

 resin, chlorophylle, &c. The vascular bundles, on the other 

 hand, seem to have no apparent connection with the crystalline 

 formations. 



We shall first attend for an instant to the form of these crys- 

 tals. This, their great minuteness makes it very difficult to 

 determine, for nothing definite can be stated on this point, if 

 we cannot determine the angles which the different surfaces 

 make with each other. To effect this object, M. Raspail 

 has invented his microscopic goniometer ; but this instru- 

 ment is too difficult to manage, since the limits of its errors may 

 be less than the differences which exist between the different 

 vegetable crystals. This will easily be conceived, if we re- 

 flect that the largest crystals which I have examined were 

 not longer than 0,11 of a Vienna line; and a great number 

 were only 0,023, and smaller than this down to their being in- 

 finitely small. The results which I have obtained on this point 

 perfectly agree with those of M. Raspail. I have given figures, 

 as accurate as possible, of the crystals I found in the following 

 plants, viz., Ficiis Be?igalensif, Maranta zebrina, Musa para- 

 dislaca, M, coccinea, Yucca gloriosa, Sireliizia regina. Papy- 

 rus antiquorurri; Triioma uvaria. Aloe pulchra. In these vege- 

 tables, the crystals are isolated, or at all events free in the inte- 

 rior of the cellules; often, however, they are grouped, and even 

 soldered together, as may be observed in many Rhubarbs^ also 

 in the Myriophyllum spicatum, Hermaria glabra, Mercurialis 

 perennis. Viburnum Lantana, Cactus pendidus^ and the Cala- 

 dium nympheafoUum. 



The chemical examination of these bodies does not present 

 fewer difficulties than the determination of their physical forms. 

 Buchner, Schlibler, Saigey, De la Fosse, Nees d'Esenbeck, and 

 Raspail are the only individuals who have engaged in the in- 

 vestigation. Their bases appear to be lime, magnesia, and 

 more rarely, silica. With them the carbonic, oxalic, phospho- 

 ric, and tartaric acids combine. The process which I employed 



