THE VEGETABLE CELL. o7 



the walls of the vessels, the cells of the wood, of the pith, of the 

 inner part of the petiole, and of tliick leaves. It usually adheres 

 firmly to the cell-wall, and can be discovered even at first in the 

 form of a tliin granular coat, coloured yellow by iodine, when the 

 cell-wall is dissolved in sulphuric acid ; in particular cases it ap- 

 peared to me not to be so firmly connected, but to be dissolved 

 and to assume before it vanished the form of an irregular net of 

 fibre-like streaks. On the other hand, the primordial utricle re- 

 tains its complete integrity throughout the whole life of those 

 cells which contain chlorophyll, thus especially in the cells of 

 leaves, and in those of the fleshy rind of the Cacte«, Enpltorhke, 

 &c., and in like manner in the cells of many Cellular plants, par- 

 ticularly of the Algse. 



Ohserv. It was natural enough that tlie primordial utricle should have 

 been seen by others before I called attention to its existence ab an miiver- 

 &ally prevailing structin^e; m particular, Kiitzing (LimiteiV, 1841, 54.6, 

 '^Fhycologia generalise'' 38) had discovered it in the Algse, and described it 

 as a special coat of the cell under the name of the Amylid-Gell. Re applied 

 this unsuitable name under the idea that its substance was changed into 

 starch by the action of potash, which is not the case. Karsten had de- 

 scribed the same hi his ^^ I) isserkitlo de cella Vitali,'^ hxit attributed import 

 to it quite different from that I have, since he considered it to be a secon- 

 dary cell. ISTageli (^^Zeitschriftf. wiss. Botaii.'^ L 9 6) had detected it in the 

 Algse, but taken it not for a membrane, but a layer of mucilage, — a view- 

 in wliich Schleiden appears to participate. I must declare against this 

 opinion in Mo. No fixed Hmit can, of coui'se, be indicated between a soft 

 membrane and a compact layer of mucilage, but a layer 

 from which (as will be described more minutely farther 

 on) folds grow out and cause constriction of the conteiits 

 of the cell, certauily must be regarded as a membrane, 

 and not a layer of fluid mucilage. 



In the centre of the young cell (fig. 44), with rare 

 exceptions, lies the so-called nucleus cellulm of Rob. 

 Brown (''Zellen-kern;" "Oytoblast" of Schleiden) ; 

 the origin of this will be treated more minutely here- 

 after in the description of the origin of cells ; it is 

 usually of very considerable size in proportion to 

 the magnitude of the young cell, so that in parti- 

 cular cases, e. g,, in the cells of jointed hairs, it almost 

 fills up the cavity. The remainder of the cell is 

 more or less densely filled with an opake, viscid 

 fluid of a white colour, having granules intermin- 

 rfed in it, which fluid I call protoplasm ( '' On the ceii from the htun 

 Momment of Sap in the InteHor of the Gelir—Bot ISf^iCr'^'"' 

 Zeitung, 1 846, 73). This fluid is coloured yellow by 

 iodine, coagulated by alcohol and acids, and contains albumen in 

 abundance, whence young organs are always very rich in nitrogen. 



