398 



Ver/ctable Physiology. 



(fig. 13, B) ; when the granules are crushed down, it is recog- 

 nised that these streaks are the lines of union of a number of 

 irregular granules, each with its own "point" connected firmly 

 together into a compound granule. 



Starch is found in the seeds of beans and peas, in the form 

 of roundish granules (fig. 2), with indistinct striation, and having 

 the internal substance very soft, so that when they are dried the 

 central cavity becomes comparatively very large, running out into 

 wide cracks. 



1 he starch of the rootstocks of the plants of the arrow-root and 

 ginger families, yielding the various pure starches known by the 

 names of " arrow-root " and " tons-lcs-mois," furnishes a number of 

 round and highly-developed forms of the starch-granule. In 

 tous-les-mois the granules are somewhat like those of a potato, 

 but much larger and with more regular and delicate concentric 

 streaks. The starch sold as arrow-root is derived from various 

 plants, but the grains of genuine kinds are mostly recognizable, 

 being very unlike those of potato, tous-les-mois, or the cereals. 



Tlie starch of maize, at least in part, and that of rice, present 

 peculiar conditions. In maize (fig. 14) the granules found loose in 

 the inner cells of the seed are small and more or less rounded, but 



Fig. 14. 



Fig. i; 





starch of maize : a, j'ourig cell with the nascent staroh-gianiiles im- 

 bedded in the formative protoplasm ; b, full-grown cell with the 

 perfect starch-granules densely packed ; c, fragment of a similar cell 

 treated with solution of iodine, which colours the starch-granules blue, 

 and the intervening protoplasm brownish yellow ; d, free starch- 



I granules, from a cell where they are not compressed through crow d- 

 ing. All magnified 400 diameters. 



Cell of rice-grain, showing 

 the very numerous small 

 starch-granules so densely 

 packed that they form a 

 solid horny mass. Mag- 

 nified 400 diameters. 



