824 



STARCHES OF MARANTACE^. 



to the comers of the distal margin of dome-shaped grains, and delicate radiating ones from the 

 hilum of the roimd grains. The gelatinized grains are swollen and somewhat distorted, but bear a 

 general resemblance to the untreated grain. 



The reaction begins immediately with ferric chloride. A few grains are gelatinized in a minute, 

 about one-third in 2 minutes, about two-thirds in 5 minutes, about seven-eighths in 10 minutes, and 

 all but rare resistant grains in 15 minutes, in which the reaction is usually complete in 25 minutes, 

 rarely 32 minutes. The reaction is quaUtatively the same as in M. arundinacea. The gelatiniza- 

 tion of the grains more often follows the second type described for M. arundinacea, the chief point 

 of difference in this reaction being that the border which forms around the grain advances towards 

 the hilum more rapidly from the sides and proximal end than from the distal margin. In dome- 

 shaped grains with pointed distal margin, gelatinization with distension of the capsule often starts 

 at the central, sharp comer of this margin. The gelatinized grains are much swollen and some- 

 what distorted, but retain the general shape of the untreated grain. 



The reaction with Purdy's solution begins in a few grains in a minute. Only a very few 

 scattered grains are gelatinized in 5 minutes, not more than about one-fiftieth in 15 minutes, very 

 slight progress in 30 minutes, and about one-tenth gelatinized in 60 minutes. The reaction is qual- 

 itatively the same as in M. arundinacea, except that: (1) since the grains differ so in shape, the 

 arrangement of the fissures is not the same, but similar, deeper, and more clear-cut than those 

 described in the reaction with pyrogallic acid; (2) gelatinization in the dome-shaped grains with 

 squared base proceeds more rapidly towards the corners at the distal margin and the proximal end 

 than in the central part of the distal margin. Rare ovoid grains appear in which gelatinization has 

 progressed further towards the distal end than the proximal, but it is not complete. The gelatinized 

 grains are swollen, but retain the shape of the untreated grain. 



STARCH OF MARANTA LEUCONEURA. (Plate 89, fig. 531. Chart 349.) 



Histological Characteristics. — In form the grains are usually simple, chiefly isolated ones which 

 have been the components of small aggregates. There are rare compound grains of few components 

 and a very few small aggregates. Most grains have pressure facets. The grains are usually regular, 

 but occasionally a small protuberance is observed near the proximal end in the large grains. The 

 conspicuous forms are dome-shaped with either squared 

 or pointed base, round, and polygonal; also few large, 

 ovoid, pyriform, clam-shell-shaped, oyster-shell-shaped, 

 and club-shaped. The smaller grains (which form the 

 largest munber) are more regular than those of M. arun- 

 dinacea and differ generally in shape and in the frequent 

 appearance of pressure facets. The smaller are not flat- 

 tened, the larger are usually ovoid in shape when viewed 

 on edge. 



The hilum is a clear, roimd spot, usually centric, 

 slightly eccentric, or rarely quite eccentric. The eccen- 

 tricity may range from six-thirteenths to one-sixth of 

 the longitudinal axis. The hilum is usually not fissured, 

 but occasionally a small transverse fissiu-e is observed in 

 the large grains. The hilum is less frequently fissured 

 and usually less eccentric than in M. arundinacea. 



The lamelloe are not demonstrable in the small, dome- 

 shaped, and round grains. They are distinct in the rather 

 large ovoid, triangular, and shell-shaped grains, forming 

 delicate circular rings around the hilum and following 

 the outline of the grain nearer the distal end. Large ovoid grains have 32 delicate lamellse, and 

 on the rounded triangular and clam-shell-shaped grains 20 to 26 have been counted. The lamellae 

 are demonstrable on a much smaller number of grains than in M. arundinacea, but are similar in 

 character to those found on the grains of that species. 



The grains vary in size; the smaller are 2 by 2/x; the larger dome-shaped are 13 by 12;*; the 

 larger, round grains are 14 by 14/i, in length and breadth. The common size for the dome-shaped 

 grains is 10 by Sp, and of the round 10 by 10^ in length and breadth. The larger of the scattered 



aart No. 349. 



P IGV T 

 S 



Curve of Reaction- Intensities of Starch of Maranta 

 leuconeura. 



