. Text-book of botany, morphological and physiological. Botany. THE CELL-WALL. 31 that it consists of solid micellae of definite form, each of which is surrounded by an en- velope of water, and is thus separated from the adjoining micellae; the more watery a cell-wall-layer, the smaller, according to the principles laid down by Nageli \ are the solid micellae, the more numerous and the thicker their aqueous envelopes. From this it follows that a certain quantity of water is as indispensable to the growth and to the in- ternal organisation of the cell-wall as is cellulose itself. This water may
. Text-book of botany, morphological and physiological. Botany. THE CELL-WALL. 31 that it consists of solid micellae of definite form, each of which is surrounded by an en- velope of water, and is thus separated from the adjoining micellae; the more watery a cell-wall-layer, the smaller, according to the principles laid down by Nageli \ are the solid micellae, the more numerous and the thicker their aqueous envelopes. From this it follows that a certain quantity of water is as indispensable to the growth and to the in- ternal organisation of the cell-wall as is cellulose itself. This water may be designated water of 'organisation, in the same sense as we speak of * water of crystallisation;' and as the latter is indispensable to the formation of many crystals, so is the former to the structure of the cell-wall. It is moreover, as we shall see, a peculiarity of all organised structures to contain this water of organisation, at least as long as they continue to grow, because they all alike grow by intussusception. From what has been said it will easily be seen that the concentric formation of layers of a cell-wall growing by intussusception differs essentially from the repeated. FiG. 33.— Macrospores of Pilulariaglobulifera, in optical longitudinal section; A a still unripe spore, in which the outermost gelatinous layer of the cell-wall is still wanting, though present in the ripe spore B; the two outermost layers of the cdl-wall of the latter (c and d) have assumed a prismatic structure, especially in c; in a? stratification is feebly indicated at the same time. Seen from the surface the prisms appear like areolae. The boundlng-surfaces of the prisms are, in the corresponding cell-wall layer of Marsilia Saivatrzx, more solid and cuticularised, by which the appearance of a honey-comb is produced. (The layers b, c, a»d d together form the epispore.) (See also Book II., RhizoearpeEe.) formation of a cell-wall round one and the same protoplasm-mass; cell-walls enclose
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
