STARCH GRAINS. 



35 



In reference to their size it will suffice to glance at Fig. 78, to show that it varies 

 very greatly, and that it is very small in the rice (Fig. 78 a), and very large in the Tous 

 les Mois (Fig. 78 b] ; whilst wheat (Fig. 78 c) and potato (Fig. 78 d] starch occupies a 

 medium position. The ordinary figure is rounded or oval, sometimes much flattened, as 

 in the Curcuma leucorrhiza, or East Indian arrow-root ; less flattened, as in the wheat 

 and barley ; oval and roundish, as in the potato and the pea (Fig. 78 t). The figure, 

 however, although permanent in 

 each variety is. its general charac- 

 acteristics, varies considerably. 

 In every specimen a multitude of 

 smaller or imperfectly-developed 

 granules will be observed; and 

 they do not assume the form 

 which is obtained by the perfect 

 granule. The consideration of 

 the markings and their nature is 

 the most interesting and impor- 

 tant part of the subject, inasmuch 

 as they are most permanent, and 

 imply an acquaintance with the 

 structure of the cell. "We shall 

 therefore say a few words in re- 

 ference to the composition of the 

 starch grain before we describe the 

 markings which distinguish the 

 various kinds of starch. 



A reference to Fig. 78 will 

 show that in almost all instances 

 there is a central spot (Fig. 

 78, 1), called the hole or hilum, 

 and that a series of lines arrange 

 themselves around it. This will 

 be better seen in Fig. 78 c, which 

 represents the cell much more Fig. 78. The more common forms of the starch cell, 

 highly magnified. The nature of f ** TSS^SSlgSft^,. 



c, wheat, do., do., faintly marked with concentric lines. 



d, potato ; medium size, flattened, and with well-inarked 



lines. 



e, the same, more highly magnified, so as to show the 



nucleus, 1, and the markings, 2. 

 /, Tout les Hois, the largest kind of starch, of oval shape, 



well-developed markings, and sometimes with a double 



hilum, 1. 

 g, the same, ruptured by the application of heat, so that 



the membrane at h is retracted and corrugated, and the 



contents exposed. 

 t, the starch of the common pea (Pisum), with its deep 



central folding or cavity. The precise figure of thui 



cavity or folding differs in various grains. 



both of these is the point in dispute. 

 There is a cell-wall, as may be 

 seen in Fig. 78 y, in which, on the 

 application of heat, it has rup- 

 tured, and is a little reflected. 

 But is there no central cavity, and 

 do the lines observed on the gra- 

 nules correspond with layers 

 within the cell-wall ? There 



have been two leading views on 

 these points. 



1st. That the starch granule is really a vesicle or cell, having an inclosing wall 

 differing in consistence, and perhaps in chemical characters, from the starch-itsel 



