. Text-book of botany, morphological and physiological. Botany. THE CELL-SAP. 63 obtained by pressure or boiling, it precipitates spontaneously after some time in the form of a white fine-grained precipitate. From solutions it crystallises in the form of so- called Sphere-crystals (Fig. 51 A), consisting of crystalline elements disposed in a radiate manner. Within the cells it may be made visible as a finely granular precipitate by drying or by rapid removal of water by alcohol (Fig. 51, F). It is abundantly pre- cipitated in the cells on dipping thin sections of the tissue into alcohol, in th
. Text-book of botany, morphological and physiological. Botany. THE CELL-SAP. 63 obtained by pressure or boiling, it precipitates spontaneously after some time in the form of a white fine-grained precipitate. From solutions it crystallises in the form of so- called Sphere-crystals (Fig. 51 A), consisting of crystalline elements disposed in a radiate manner. Within the cells it may be made visible as a finely granular precipitate by drying or by rapid removal of water by alcohol (Fig. 51, F). It is abundantly pre- cipitated in the cells on dipping thin sections of the tissue into alcohol, in the form of smaller sphere-crystals which become readily visible on addition of water (Fig. 51, B). They are obtained much larger by laying entire specimens of Acetahularia or large pieces of tissue containing inulin (tubers and stems of the dahlia or Jerusalem artichoke) for a longer time in alcohol or glycerin; in the latter case a sphere-crystal very commonly includes several cells of the tissue (Fig. 51, E), a proof that the crystalline arrangement is not necessarily destroyed by the cell-walls. Similar forms (as in Fig. 51, B) are formed when tissues containing inulin freeze; and they do not again become dissolved in the cell- sap on thawing. Since the sphere - crystals consist of doubly refractive crystalline elements arranged radially, they show, with polarised light, the characteristic cross. They are not capable of swelling, are slowly dissolved in a large quantity of cold water, rapidly in a small quan- tity of warm water of from 5o°-55° G.; in nitric or hydro- chloric acid or potash solu- tion they dissolve easily, the solution always commencing from without; by boiling in very dilute sulphuric or hydro- chloric acid the inulin is im- mediately transformed into glucose. Solutions of iodine in alcohol or water penetrate into the fine crevices of the sphere-crystals, but produce no special colour. Inulin-structures are easily and certainly recognised by these re- actio
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
