. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. cleus lends a hand. We conclude that the leucoplasts make the starch becauseit first appears as a very minute granule within the leucoplasticbody and gradually attains to its full size there. The leuco-plasts absorb the glucose and readjust its elements into themore complex starch. We note the fact but cannot tell howit is accomplished, nor the steps in the process. As fast asthe glucose is thus taken out of solution more comes to theleucoplasts by diffusion, and the process adva
. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. cleus lends a hand. We conclude that the leucoplasts make the starch becauseit first appears as a very minute granule within the leucoplasticbody and gradually attains to its full size there. The leuco-plasts absorb the glucose and readjust its elements into themore complex starch. We note the fact but cannot tell howit is accomplished, nor the steps in the process. As fast asthe glucose is thus taken out of solution more comes to theleucoplasts by diffusion, and the process advances until theleucoplasts are stretched to an almost or quite invisible filmoutside the starch grain. If the starch grain makes its beginning at the center of theleucoplast the successive layers are about of equal thicknessall around and the grain becomes concentrically striated, asin the garden bean; but if the grain starts outside the centerthe additional layers are formed faster, and so become thicker,on the side of the greater amount of leucoplastic substance, aswe find them in the Irish potato (Fig. 101).. PROCESS OF STORAGE 185 Sometimes it happens that the starch begins to be deposited atmore than one point in the leucoplast, so that two or more rela-tively small grains become closely associated, and adhering withmore or less tenacity they constitute a compound grain (Fig. 101). In storage tissues, where simple grains are the rule, com-pound grains may also occur; and in some instances, as in oatsand rice, compound grains are the some cases small units of starch maybegin to form a compound grain andthen all become encased in a commonstarch sheath deposited by the exteriorpart of the leucoplast. These grainsare called half-compound. FlG- 101.—showing con- . , centric and excentric stria- The storage of oils and fats takes tions of starch grains. e,place in the vacuoles and throughout potat° s*arch excefrically striated; /, compound starch the meshes Of the Cyto
Size: 1858px × 1345px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookcollection, bookdecade1910, bookyear1910
