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could be precipitated by double decomposition f.-om its solution, as an 

 insoluble amylate of lime, baryta, lead, or silver, and thus pure starch 

 was readily obtained for the purpose of analysis. Being an insoluble 

 body, starch could be taken up by the juices of the plant in that con- 

 dition, but when required for use was converted into dextrine and 

 sugar, which, being soluble substances, could be immediately 

 employed for the nourishment of the plant. Unlike chloro- 

 phyll, which would only develope in structures exposed to the light, 

 starch was always found most abundantly in those parts which were 

 deep-seated and removed from the light. 



A fully-formed starch granule usually presented a small rounded 

 spot called the hilum, generally situated at one end, around which were 

 grouped a number of concentric lines, which might be made more 

 evident by careful dessication. This appearance had given rise to a 

 large amount of discussion as to what was the real nature of a starch 

 granule. Some observers maintained that the granule was a true cell 

 filled with a substance which was alike throughout, that the hilum was 

 an opening into this cell, and that the appearance of lines was caused 

 by the unfolding of the walls of the cell. In support of this view Bush 

 gave the following experiment. Saturate a few granules with a strong 

 solution of chloride of zinc, having a small quantity of iodine mixed 

 with it. On the addition of a small quantity of water the granules 

 would gradually expand, developing at the same time a frill-like 

 plicated margin, which slowly opened out ; the plications on the granule 

 might then be seen slowly imfolding, and might be traced in many 

 cases into the rugee of the frill. The granule at length swelled up to 

 twenty or thirty times its original bulk, appearing as a flaccid sac, 

 though no extrusion of matter could be observed during the experiment. 

 Other observers considered that the granule was a cell, and 

 that the hilum was an opening into it, while the concentric 

 lines were caused by successive deposits extending from the 

 nucleus to the outer wall, and varying in density, the outer 

 layer being most compact. In support of this view the fol- 

 lowing experiment was given. If a little potato starch was 

 heated on a metal plate to 360 degrees or 390 degrees, and then 

 examined after treatment with a little water, the several layers would 

 be found swollen, and by adding an aqueous solution of iodine they 

 would be made to appear with considerable distinctness. Reid 

 saturated starch granules with glycerine, and placed them while in this 



