GENUS BRODI^A. 



603 



The lamdla are fairlj- distinct, regular, coarse, continuous rings, following the outline of the 

 margin. Those near the distal end are usually coarser than those near the hilum. They vary in 

 size and distinctness in different grains. There are 10 to 12 lamellae on the larger grains. 



The grains vary in size from 3 to 40a(. The common size is 24^. 



Polariscopic Properties. The figure is eccentric, very distinct, not always clear-cut. The lines 

 are thick and become thicker as they approach the margin. If there is a cavity or fissure at the 

 hilum the lines of the figure may not meet at this point. In some cases one of the lines is seen to 

 be bisected. This may occur when the line extends longitudinally along the middle of the grain. 



The degree of polarization is high, especially if the grain is viewed from the end ; but in some 

 of the grains it appears to be low or absent near and at the margin. It varies also in different grains. 

 It is slightly higher than in the grains of B. peditncularis. 



With selenite the quadrants are well defined, regular 

 in shape, and unequal in size. The colors are pure. 



Iodine Reactions. With 0.25 per cent Lugol's solution 

 the grains are colored deeply a blue-violet; with 0.125 per 

 cent solution the grains tint fairly. The reactions are more 

 than those of B. peditncularis. After heating until the grains 

 are completely gelatinized, the solution colors fairly and 

 the grains deeply on the addition of iodine, and the grains 

 are much swollen and distorted. After boiling for 2 min- 

 utes the solution is much more deeply colored, but the grain- 

 resitlues much less, some not at all. On the addition of more 

 iodine the capsules color a red-violet, and some blue-react- 

 ing starch may be seen, usually in the proximal end of the 

 capsule. The distal end is empty, twisted, and crumpled. 



Stairiing Reactions. With gentian violet the grains 

 stain at once fairly well and after 30 minutes are fairly 

 deeply stained, yet not deeply. They are stained much 

 deeper than the grains of B. peduncularis. 



With safranin the grains stain at once lightly and 

 after 30 minutes the color is fair. The grains are more markedly colored than those of B. peduncularis. 



Te77iperature Reaction. The temperature of gelatinization is 65 to 66 C, mean 65.5. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in some small grains 

 in a minute and about half show some reaction in 10 minutes. Almost all are completely gelatinized 

 in 50 minutes and all but 2 or 3 in 70 minutes. There is no further change. The reaction is quali- 

 tatively the same as that of the grains of B. peduncularis. 



Reaction with chromic acid begins immediately in the smaller grains and in 30 seconds in the 

 larger, and all the grains are completely dissolved in 10 minutes. The reaction is qualitatively 

 the same as that of the grains of B. peduncularis. 



The reaction with pyrogallic acid begins in a few grains in a minute and in all in 15 minutes. 

 All the grains are partially gelatinized in 30 minutes, but the reaction is incomplete in an hour. 

 The reaction is qualitatively the same as that of the grains of B. peduncularis. 



With ferric chloride the reaction begins in the smaller grains in a minute, half the total number 

 are affected in 10 minutes, and all are completely gelatinized in an hour. The reaction is qualita- 

 tively the same as that of the grains of B. peduncularis. 



Reaction with Purdy's solution begins in some few grains in 45 seconds, all are affected in 7 

 minutes, and all partially gelatinized in an hour. The reaction is qualitatively the same as that 

 of the grains of B. peduncularis. 



STARCH OF BRODIiEA CONGESTA. (Plate 48, figs. 287 and 288. Chart 182.) 



Histological Characteristics. In foTTn the grains are simple, with the exception of a few com- 

 pounds which consist of two or more components. There are very few aggregates, even among the 

 smaller grains, but there is a marked tendency to form large clumps. The surface of the grains is 

 almost without exception very regular, showing the least irregularity of all the Broditeas. The most 

 conspicuous forms are the ovoid to round, oval, and ellipsoidal. The grains are not flattened in any 

 transverse diameter, hence they are as thick as broad, and appear round when seen on end. 



Curve of Reactioti'Intensities of Starch of Brodisa 

 capitata. 



