. Principles of the anatomy and physiology of the vegetable cell. Plant cells and tissues. Cells of the albumen of Sagu<i fcedigera. Fig. 16. that tlie membrane of tlie young cell and likewise the inmost layers of full grown cells are composed of cellulose^ the intermediate and outermost layerS; on the con- p, -^ trary, of other com- pounds, which are subsequently form- ed and deposited on the outside of the cel- lulose membrane. Against this I have shewn (^^Botanisclie 2^eitunf 184:7,4:97) that the chemical researches by which their deductions are supported; were im- perfect ; that the out
. Principles of the anatomy and physiology of the vegetable cell. Plant cells and tissues. Cells of the albumen of Sagu<i fcedigera. Fig. 16. that tlie membrane of tlie young cell and likewise the inmost layers of full grown cells are composed of cellulose^ the intermediate and outermost layerS; on the con- p, -^ trary, of other com- pounds, which are subsequently form- ed and deposited on the outside of the cel- lulose membrane. Against this I have shewn (^^Botanisclie 2^eitunf 184:7,4:97) that the chemical researches by which their deductions are supported; were im- perfect ; that the outermost layers of cell-membrane are composed in like manner of cellu- lose, but are infiltrated with foreign compounds, which prevent the re- action of iodine and sulphuric acid; that the date of origin of a layer must not be deduced from the che- mical reaction, since both the inner and outer layers may undergo a che- mical metamorphosis, which does not stand in any connexion with the time of its origin j and that therefore ana- tomical groxmds alone can serve for the decision of the order in which dif- ferent layers have been developed.— Lastly, in reference to the statement that the thick walled cells of the albumen of PhytelepJias^ Iris, &c. (figs. 14, 15), and the so-called col- lenchyma cells {^g. 16) possess uni- form, and not lamellated, walls, and that consequently their primary mem- brane itself has increased in thickness; this assertion depends simply upon im- perfect investigation. If the authors had treated these cells with sulphuric acid of the proper degree of concentration, they would have found the lameUation.—In short, the researches which I was caused to undertake by the objections of Harting and Mulder, served only to strengthen the grounds on which I had built my theory of the growth of cell-membranes. The secondary ceU-membranes deserve a separate mention. Taken altogether, it is seldom that they appear to the eye, as the primary membrane does, in t
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