370 



STARCHES OF GRAMINACE^. 



and dissolve. In normal grains fine striae appear, radiating from the hilum in all directions towards 

 the periphery. The less resistant starch passes into a semiliquid mass which occupies the central 

 part of the grain, and the more resistant starch forms a marginal ring which is finely striated, and 

 becomes a thin, transparent, homogeneous-looking capsule as the grain swells. This capsule is 

 dissolved at one or two points, and the semiliquid inclosed starch flows out and is dissolved, followed 

 by solution of the capsule. 



With pijrogallic acid the reaction begins in all the grains in from 30 to 45 seconds and is over 

 in IM minutes. The hilum and lamella; become very distinct, and fine stria; ajipear radiating from 

 the hilum in all directions. The grain swells, but the less resistant starch, whose early gclatiniza- 

 tion is the i^rimary cause of the swelling, does not collect in the center, but remains ilistriliutetl 

 throughout the grain, and the more resistant starch also remains in place, so that there are in the 

 swollen grains several striated, concentric bands separated by clear spaces. These bands become 

 clearer, until in manj' grains it is very difficult to distinguish them. The gelatinized grains are 

 large, clear, and often retain much of their original form and some of their lamellar markings, while 

 the capsules of others are folded and wrinkled. 



The reaction with ferric chloride begins in a few grains in ^^ minutes. In 30 minutes about 

 half of the grains are completely gelatinized, and in an hour nearly all are completely gelatinized. 

 The reaction begins at several points on the margin. The starch at these parts gelatinizes and swells 

 irregularly, and the process extends inward over the rest of the grain. In some cases tlie process 

 at first affects all the starch of the margin, and then proceeds inward. The central starch mean- 

 while becomes granular and rather clear. The swollen grains are large and do not retain much of 

 their original form. The capsule is usually much wrinkled and folded. 



The reaction begins in some of the grains in a minute with Purdy's solution. A few grains are 

 partially gelatinized in 20 minutes, but there is not much further change in an hour. The reaction, 

 as far as it goes, is much like that with pyrogallic acid, the main difference Ijeing that with Purdy's 

 solution the marginal starch appears more sensitive to the reagent than the central starch. 



STARCH OF SECALE CEREALE VAR. (SPRING). (Plate 2, figs. 11 and 12. Chart 18.) 



Histological Characteristics. In form the grains are usually simple and for the most part iso- 

 lated. There are some aggregates which consist usually either of numerous minute grains, or of 

 one large grain with several very small ones adhering to it. The conspicuous forms, lioth of the 

 large grains and small grains, are the same as those noted 

 for Mammoth Winter rj'e. 



In some of the medium-sized grains the hilum may be 

 distinguished as a clear spot which is centric or slightly 

 eccentric in position. Usually the hilum is not visible. 

 Quite often either an irregular cavity or clefts are found 

 in the region of the hilum similar to those noted under 

 Mammoth Winter rye. 



The lamellce, both as to number and character, closely 

 resemble those of Mammoth Winter rye. 



The grains vary in size from the smaller, which are 

 2 by 2ju, to the larger, which are 48 by 48^ and 40 by 40/j. 

 The common size is 28^1. 



Polariscopic Properties. The figure is usually centric 

 and is distinct in the medium-sized and small grains. It 

 is distinct in a larger proportion of large grains than in 

 Mannnoth Winter rye. The figure and lines are the same 

 as noted for Mannnoth Winter rye. 



The d(;gree of polarization is low to fairly high when 

 grains are vii:wed on the (lat, and quite high when viewetl 

 on edge. It is on the whole low, but somewhat higher in a greater proportion of grains than in 

 ]\Iammoth Winter rye. 



With selenite the quadrants and the colors are the same as those noted for Mammoth Winter rye. 



Iodine Reactions. With a 0.25 per cent Lugol's solution, the grains all color a fairly deep blue 

 to a reddish-violet; with a 0.125 ptT cent solution they are lightly colored. The coloration is the 



I GV 7 P 

 S 



Chart No. 



GV S T CI 



18. 



Cl PA 

 PC PS 



Curve of Reaction-Intensities of Starch of Secale cereale 

 var. (Spring). 



