Figs. 22 and 23 have an extremely irregular polyhedral or distorted granules, often united in groups with smaller granules and adherent to the larger ones. In size, it varies from .001 to .025 millimeter, averaging nearly the latter size. In some granules the hilum can be distinguished, but no rings; it is readily detected with polarized light. BUCKWHEAT STARCH Fig. 24 is very characteristic. It consists of a chain or groups of angular granules with a not very evident circular nucleus and without rings. The outline is strikingly angular and the size not very variable, being about .01 to .015 millimeter. MAIZE OR CORN STARCH Figs. 25 and 26 have granules largely of the same size from .02 to .03 millimeter in diameter, with now and then a few which are much smaller; they are mostly circular in shape or, rather, polyhedral with rounded angles. They form very brilliant objects with polarized light, but with ordinary illumination show but the faintest signs of rings and a well-developed hilum, at times star-shaped and at others more like a circular depression. RICE STARCH Figs. 27, 28, and 29, is very similar to corn starch, and is easily confused with it, being about the same size. It is, however, distinguished from it by its polygonal form and its well-defined angles. The hilum is more prominent and more often stellate, or linear, and several grains are at times united. [Illustration: Fig. 22. PURE CINNAMON Fig. 23 _Cinnamon_ Fig. 25. MAIZE STARCH Fig. 26 _Corn_ Fig. 41. PURE CASSIA] [Illustration: Fig. 30. WHEAT STARCH Fig. 31 _Wheat_ Fig. 32. BARLEY STARCH Fig. 33 _Barley_] WHEAT STARCH Figs. 30 and 31 are quite variable in size, varying from .05 to .012 millimeter in diameter, and this starch belongs to the same class as barley and rye; the hilum is invisible and the rings are not prominent; the granules are circular disks in form, and there are now and then contorted depressions, resembling those in the pea starch; it is the least regular of the three starches and does not polarize actively. BARLEY STARCH Figs. 32 and 33 are quite similar to that of wheat, but barley starch does not vary so much in size, averaging .05 millimeter. It has rings more distinct and very small granules adhering to the largest in bud-like forms. RYE STARCH Fig. 34 is more variable in size, many of the granules not exceeding .02 millimeter while the largest reach .06 to .07 millimeter. It lacks distinctive characteristics entirely, and is the most simple in form of all starches described. OAT STARCH