818 



STARCHES OF MARANTACEiE. 



protuberances and in elongated ellipsoidal grains having the hilum located in the middle of one side. 

 In the grains with a large, cone-shaped protuberance at the proximal end, gelatinization with dis- 

 tension of the capsule begins at this end, followed rather rapidly from the distal end, the starch of 

 the region surrounding the hilum being the most resistant. In the elongated, ellipsoidal grains 

 above noted, gelatinization begins simultaneously at both ends. The gelatinized grains are much 

 swollen but retain the general shapes of the untreated grain. 



Reaction with Purdy's solution begins in a few grains in 30 seconds. About one-fortieth are 

 gelatinized in 5 minutes, about one-twentieth in 15 minutes, about one-sixteenth in 30 minutes, 

 and about one-eighth in 60 minutes. The hilum swells, but generally no bubble appears; the fis- 

 sures are similar in character and arrangement to those described for the resistant grains when 

 treated with pyrogallic acid, but are much deeper and more clear-cut. The lamellae are sharply 

 defined and striated, and during their disorganization refractive granules appear, which are less 

 resistant and irregularly massed around the hilum and center of the grain, but linearly arranged 

 near the distal margin and also at the proximal end, when they appear at this point. Gelatinization 

 proceeds more rapidly from the hilum to the distal end between two coarser, radiating fissures, 

 between which there is a cluster of delicate fissures. Or the starch at the proximal end and sides 

 nearby, usually being the most resistant, often remains as a homogeneous, solid border in the other- 

 wise gelatinized grain, but sometimes it breaks into fairly large, irregular fragments which may 

 persist or gradually gelatinize; or this border may become differentiated into sharply defined and 

 striated lamellae, which, if they become disorganized, result in the appearance of linearly arranged, 

 refractive granules. The gelatinized grains are swollen, but retain the general shape of the untreated 

 grain, and there is usually either a trace of a few lamellae or some refractive granules present. 



STARCH OF MARANTA ARUNDINACEA VAR. No. 1. (Plate 88, figs. 525 and 526. Chart 346.) 



Histological Characteristics. — In form the grains are simple, excepting some rare compounds 

 consisting of two components; there appears no tendency to form aggregates or clumps, and pres- 

 sure facets are rare. The surface of the grains tends to be more or less irregular, owing to rounded 

 protuberances, nipple-like processes, and spicules, which are most commonly found at the distal 

 end of the grains. The most conspicuous forms are ovoid to oval and elliptical, clam-shell-shaped, 

 mussel-shell-shaped, triangular with rounded angles, and spherical; also pyriform, quadrangular 

 with rounded angles, elongated dome-shaped, and various 

 regular forms. The proximal may be the broader or 

 narrower end, but when the grain is seen on edge the 

 distal end is the narrower. When viewed on end the 

 grain is ovoid to spherical at the proximal end, and 

 narrow and irregularly elUptical at the distal end. The 

 ovoid to the oval and elliptical forms are commonly from 

 about one-half to two-thirds as broad as long, but the 

 shell-shaped and allied forms may be broader than long. 



The hilum is a small, round, non-refractive spot, usu- 

 ally eccentric about one-sixth to one-fourth of the longi- 

 tudinal axis. It may be in or somewhat to one side of 

 the median Une. It is sometimes marked by a short, but 

 deep, transverse fissure having a double curve, and the 

 fissure may be divided at the ends into several smaller 

 fissures; or it may be crossed by another fissure to form 

 a 2-armed figure. Compound grains with 2 hila are seen, 

 and the line of junction of the component grains may be 

 indicated by a linear depression or a fissure. 



The lameUoe are continuous circles or arcs of circles, 

 which are often irregular as they follow the outline of the margin. They are not usually very 

 distinct and are rather coarse. They vary in size and spacing in the same grain and in different 

 grains, and those added last are often the largest and most distinct. They may be wavy in outline 

 without reference to the form of the margin of the grain, and vary in number, averaging about 23 

 on the larger grains. 



The grains vary in size from 11 to 54;t, The conunon size is 20^. 



Curve of Reaction-Intensities of Starch of Maranta 

 arundtnacea var. No. I. 



