GENUS MARANTA. 817 



Temperature Reaction. The temperature of gelatinization is 7G to 78 C, mean 77. 



Effects of Various Reaycnts. With chloral hydrate-iodine reaction begins immediately. A few 

 grains are gelatinized in a minute, nearly all in 2 minutes, all but a few resistant grains in 3 minutes, 

 in which the reaction is usually complete in 6 minutes, rarely not until 7 minutes. The grains color 

 an old-rose at once, and the hilum appears as a dark spot, ring, or lines. Gelatinization accompanied 

 by a dark bluish color begins at the distal end, or at any prominent corners or jjrotuberances on 

 the grain, quickly spreads around the margin and then advances more rapidly from the distal mar- 

 gin towards the hilum than from other points, the region of the hilum being the last to undergo 

 the reaction. The grain is deeply colored, uniformly and slightly swollen, but retains the general 

 shape of the untreated grain. 



Reaction with chromic acid begins immediately. Several grains are dissolved in a minute, nearly 

 all in 2 minutes, and all but parts of a few resistant grains in 3J^ minutes, in which the reaction is 

 usually complete in 43-2, rarely 5\4, minutes. The structures at the hilum swell and a bubble ap- 

 pears which enlarges and then collapses, followed in most grains by a rapid disorganization of the 

 surrounding region, accompanied by the appearance of an irregular mass of refractive granules 

 embedded in the gelatinized starch. The outer lamelte are sharply defined and striated, and as 

 they become broken down the refractive granxiles appear first in linear arrangement; the grain 

 continues to enlarge and finally the capsule is ruptured. The rupture occurs at the distal end of 

 the narrow forms, or usually at one corner of the distal margin in the broadened triangular and 

 shell-shaped grains; which comer during the reaction becomes prominent and extended laterally. 

 The entire grain now passes into solution, the capsule of the proximal end and sides nearby usually 

 being the most resistant. An exception occurs to this method, when a large, cone-shaped extension 

 is present at the proximal end, the capsule then being ruptured first at this point, but the other 

 steps of the reaction are the same, except that from the slightly eccentric hilum, fissures extend 

 towards both the proximal and the distal ends. During the process of gelatinization in the more 

 resistant grains, two or three parallel, branched fissures in the narrower forms, and a cluster of 

 fissures with two, sometimes three, more prominent ones in the broader forms can be observed 

 extending from the hilum towartls the distal end; the steps of the process are the same as those de- 

 scribed above. 



The reaction with pyrogallic acid begins immediately. iSeveral of the grains are gelatinized in 

 10 seconds, nearly all in 30 seconds, and all in 45 seconds. The structures at the hilum swell and a 

 bubble appears which quickly enlarges and then suddenly collapses by the rapid gelatinization of the 

 grain with the exception of the outermost lamelte, which are soon gelatinized. The reaction is so 

 rapid that the various steps are difficult to determine, but in the less reactive grains, two or three 

 large, branched fissures extend distalwards from the hilum, along which gelatinization proceeds 

 with a faint trace of granules embedded in the more soluble starch until the process is complete. 

 The gelatinized grain is much swollen and the capsule is thrown into folds at the distal end, but 

 retains the general contour at the proximal end, so that it resembles the untreated grain. 



The reaction with ferric chloride begins in a few gi-ains immediately. A small number are gelat- 

 inized in a minute, about three-fourths in 2 minutes, about seven-eighths in 4 minutes, and all but 

 rare resistant grains in 5 minutes, in which latter the reaction is usually complete in 8 minutes, 

 rarely 10 minutes. The structures at the hilum become very distinct, then a bubble usually appears 

 at this point, and a lustrous border forms around the grain. This border increases in width, more 

 rapidly generally at the distal end, and gelatinization begins at the hilum in the narrower forms, 

 but at the corners of the distal margin in the broadened forms, accompanied in each type by the 

 rapid distension of the capsule. Gelatinization in the latter case proceeds towards the proximal end 

 accompanied by irregularly arranged, refractive granules embedded in the more soluble starch; 

 finally, as the reaction approaches the region of the hilum, the bubble rapidly enlarges, then col- 

 lapses, followed by the fissuration of this more resistant starch into rather large, irregular masses 

 which gradually become gelatinous. In many grains, the lustrous border gradually closes around 

 the hilum, the lamellae in this border becoming more sharply defined; the bubble at the hilum swells 

 rapidly, collapses, and gelatinization quickly spreads over the grain, with the exception of the outer 

 lamellse of the proximal end and sides nearby, which gradually become gelatinous. In grains in 

 which this process is less rapid, gelatinization is frequently accompanied by the appearance of 

 fissures extending inward from the distal end and outward from the region of the hilum. Ex- 

 ceptions of these two general types of gelatinization are found in those grains which have large 



