THE VEGETABLE CELL. 



49 



Crystals occur sometimes singly in a cell, or in numbers ii-regu- 

 larly scattered, combined into star-shaped 

 groups, or laid side by side in the form of ^w ^T. 



a bundle. The last condition (fig. 47) is 

 the most frequent, for there can scarcely 

 exist a plant in which have not been 

 found in some organs, for instance the 

 anther, or in the bark, such bundles of 

 very fine, needle-like four-sided crystals, 

 terminating at each end in four-sided py- 

 ramids (De Oandolle's " Raphides''). The 

 composition of these needle-like crystals 

 is variously given ; according to Payen 

 Sixid Schmidt, they are composed of oxa- 

 late of lime ; according to Buchner and - v^ • w ^ 

 TrincMnetti of phosphate of lime ; ac- 

 cording to NeeS von Esenbeck of a double Keedle shaped crystals, fiom the 



salt of lime and magnesia with phosphoric If^fjy&'irmg^'^^^ 

 acid. In very many plants, e g., very 



beautifully in the Rhubarb-root, occur four-sided rather obtusely 

 pointed prisms of oxalate of lime ; and moreover very frequently 

 mulberry-like agglomerations of rhombohedrons, which aie com- 

 posed of carbonate of lime, more rarely of tartrate of lime (in old 

 Cactese), and sulphate of lime (in the Musacese). (See " Unger 

 on " The FormaUon of Crystals in Vegetable Cells" in the '^ATin. 

 of the Vienna Mus/' Th ii — Payen '^Memoires sur lea JDeveloppe- 

 wsnt des Vegetaux/' — Schmidt "Sketch of a General Method of In- 

 vestigating the juices and excretions of the Animal Organism^) 



F. ORiaiK OF THE CELL. 



It is an universal law in the development of cells that the 

 contents are formed before the cell-membrane, and that the orga- 

 nization of the nitrogenous structures precedes that of the mem- 

 brane composed of cellulose. In plants, the formation of cells 

 occurs only in the cavity of older cells, and not between or upon 

 them. 



The formation of the cells takes place in two diflferent ways : 

 1, through division of older cells ; 2, through the formation of 

 secondary cells (tochter-zellen) Ijmg free in the cavity of a cell. 



Ohserv. It would be superfluous to give an accotmt of the older 

 theories of cell-formation which had existed up to the appearance of my 

 dissertation on the multiplication of yegetahle cells by di-visiou, in the 

 year 1835, since none of them were hased on any secure foundation. 

 Actual origination of cells had been observed only in poUen-grains and 

 spores, but the connexion of the formation o£ these with cell-formation in 

 general was altogether overlooked, and the emptiest conjectures had been 

 ventured as to the origin of cells from chlorophyll and starch-grannies, 



