820 



STARCHES OF MARANTACEiE. 



formed are large and ovoid and retain somewhat the original shape of the grain. The proximal 

 end is rounded; the distal is crumpled and irregular. 



With /err/c chloride reaction begins in two-thirds of the grains in 2 minutes, about seven-tenths 

 are gelatinized in 5 minutes, and practically all in 10 minutes. The reaction is complete in all in 

 20 to 35 minutes. The hilum is prominent as a dark bubble, the lamellte disappear, the margin 

 becomes clear and darker, and the inner portion of the grain appears light and opaque. The distal 

 end becomes gelatinized and has irregular protrusions. In grains in which the transverse diameter 

 is the longest (triangular and certain related forms), the two poles of this diameter become gelat- 

 inized first, then the hilum swells enormously just before or just as this process of gelatinization 

 reaches it, and the bubble which appears at the hilum during the first part of the reaction now be- 

 comes very large and then disappears. The gelatinized grains are very large, round, and smooth 

 at the proximal end, and crumpled, lobulated, and folded at the distal end. The margin is at first 

 distinct and shows indistinctly striated bands; later it becomes thin and clear. 



Reaction with Purdy's solution begins immediately and almost all of the grains are swollen in 

 2 minutes; about four-fifths are gelatinized in 5 minutes and nearly all in 30 minutes; no further 

 progress occurs in an hour. The hilum and lamellce become distinct and fine strise radiate from the 

 hilum throughout the inner portion of the grain. The hilum swells rapidly, pushing the striated 

 part before it to the distal end, where it collects as a granular mass. Some of the gelatinized part of 

 the grain is formed into a marginal band which is very distinctly marked with fine striations. If 

 the hilum is fissured and the reaction slow, the grain may be divided by deep fissures, which open 

 out in a stellate fashion as the hilum swells. The gelatinized grains are large, ovoid to elliptical. 

 The proximal end is smooth and rounded, while the distal is crumpled, lobulated, and distorted. 



STARCH OF MARANTA ARUNDINACEA VAR. No. 2. (Plate 88, figs. 527 and 528. Chart 347.) 



Hislological Charaderislics. In form the grains are simple, with the exception of a few com- 

 pounds in the form of two or three components. There is no tendency to form aggregates or clumps, 

 and pressure facets are rare. The surface of the grains tends to be irregular, owing to rounded 

 protuberances and spicular or nipple-like projections, 

 which are most frequently found at the distal end of the 

 grain. The conspicuous forms are ovoid to oval and 

 elliptical, clam-shell- and mussel-shell-shaped, pyriform, 

 triangular, spherical, and dome-shaped; also various irreg- 

 ular forms. The proximal end may be the narrower or 

 broader end. The grains are from about half to a third 

 as thick as wide, and conmionly from one-third to tlu-ee- 

 fourths as broad as long. When observed on end the 

 proximal end is ovoid to spherical or elliptical, while 

 the distal end is oval to elliptical, the distal end being 

 flattened more than the proximal. In the ovoid to ellip- 

 tical forms the longitudinal axis is longer than the trans- 

 verse, while in some of the clam-shell and related types 

 the reverse is often the case. 



The hilum is a distinct, relatively large, round, re- 

 fractive spot. Double hila are common, and three hila 

 may be seen arranged triangularlj'. It is usually eccen- 

 tric about one-sixth to one-fourth of the longitudinal 

 axis and in or slightly to one side of the median line. It 



is often fissured, and the fissuration is commonly in the form of a short, deep, transverse or longi- 

 tudinal fissure, whose ends often branch into a number of small fissures; or there may be an 

 irregular or stellate arrangement of small fissures. 



The lamellce are not very distinct. They vary greatly in distinctness and size in different 

 grains, and somewhat in the same grain. They are circles or arcs of circles, and those more distal 

 to the hilum tend to follow the outlines of the margin. In grains with double hila, two sets of lamel- 

 Ise corresponding to the hila are noted, but a short distance from the hila they are merged into one 

 another. Their number varies from 16 on the small to 38 on the large grains. The average is 22. 



The grains vary in size from 7 to 45>i. The common size is 28/^. 



arundinacea var. No. 2. 



