. The cell; outlines of general anatomy and physiology. ble to grow to such a considerable size. The solidsubstance contained by a plant very rich in water may be as littleas 5 per cent., or even only 2 per cent. THE VITAL PROPERTIES OF THE CELL 155 B The cell sap,however, is notpure water, buta very complex,nutrient solutioncontaining veget-able acids andtheir salts, nit-rates and phos-phates, sugar, andsmall quantitiesof dissolved pro-teids, etc. Thusbetween the pro-toplasm and thesap material isinterchanged toa considerable ex-tent, substancesfor use being ex-tracted from theone, which inre
. The cell; outlines of general anatomy and physiology. ble to grow to such a considerable size. The solidsubstance contained by a plant very rich in water may be as littleas 5 per cent., or even only 2 per cent. THE VITAL PROPERTIES OF THE CELL 155 B The cell sap,however, is notpure water, buta very complex,nutrient solutioncontaining veget-able acids andtheir salts, nit-rates and phos-phates, sugar, andsmall quantitiesof dissolved pro-teids, etc. Thusbetween the pro-toplasm and thesap material isinterchanged toa considerable ex-tent, substancesfor use being ex-tracted from theone, which inreturn receivesother substancesin the sap re-presents a con-centrated solu-tion of osmoticsubstances, it ex-erts a powerfulattraction uponwater, and alsoan internal pres-sure, which is of-ten considerable,upon the envelope surrounding it, thus producing a tense condition, which wasdescribed on p. 141 as turgor. Many botanists, especially de Vries (V. 35) and Went, considerthe vacuoles to be special cell organs, which are not of accidental. Fig. 62.—Parenchyma cells from the cortical layer of theroot of Fritillaria imperialis (longitudinal sections, x 650: afterSachs II. 33, Fig. 75): A very young cells, as yet withoutcell-sap, from close to the apex of the root; B cells of the samedescription, about 2 mm. above the apex of the root; the cell-sap (o) forms in the protoplasm (p) separate drops betweenwhich are partition walls of protoplasm ; C cells of the samedescription, about 7-8 mm. above the apex ; the two lowercells on the right hand side are seen in a front view; thelarge cell on the left hand side is seen in optical section ; theupper right hand cell is opened by the section ; the nucleus (r;/)has a peculiar appearance, in consequence of its beiny dis-tended, owing to the absorption of water; fc nucleus; kk nu-cleolus; h membrane. 156 THE CELL formation in the cell-bod)-, but which can only be produced bydivision. Evren in the youngest plant-cells, accordin
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