594 



STARCHES OF LILIACEyE. 



STARCH OF BRODLEA lACTEA. (Plate 46. figs. 271 and 272. Chart 174.) 



Histological Characteristics. — In form the grains are simple, wi tli the exception of a few compounds 

 consisting of two or three components; some of the smaller form aggregates. There are no pressure 

 facets on any of the isolated grains. There is some tendency to form in clumps. Rarely, 2 grains 

 occur embedded in secondary deposits to form a large grain. A few grains have small, nipple-like 

 and other processes and irregularities on the surface. The conspicuous form is the oval, with the 

 narrow end rather pointed, and ovoid. In addition there are quadrangular, polygonal, nearly round, 

 and a few pyriform grains. The grains are not flattened and they present practically the same diam- 

 eter at any given diameter as they are turned over. When viewed on end they usually appear round. 



The hilum is distinct, and when it is not fissured it appears as a small round spot, eccentric 

 about one-third of the longitudinal axis of the grain, and usually in or near the median line. There 

 may be double, or rarely triple, hila, each of which may or may not be surrounded by 2 or 3 lamellse 

 independent of the lamelljB of the others. Generally the hilum is fissured. The fissure is often very 

 small and narrow, transverse or diagonal, but generally 3-armed; very rarely it is irregularly 

 stellate. In some cases the hilum appears as a cavity with a fissure extending from it at one side. 

 It is not rare for the body of the grain to be crossed by a number of small, irregular fissures. 



The lamellce are fairly distinct, coarse, continuous, and regular. They follow closely the out- 

 line of the margin, but occasionally one or two will show independent irregularities. They vary in 

 size and distinctness in different grains, those near the 

 hilum being more distinct than those near the margin. 

 There are 8 to 10 lamellse on a medium-sized grain. 



The grains vary in size from 2 to 32^. The com- 

 mon size is 18ju. 



Polariscopic Properties. — The figure is clear-cut and 

 distinct. It is seldom bent or otherwise distorted. Its 

 lines do not, as a rule, become broader and less well 

 defined at the margin. Often the main peculiarity is 

 the failure of the lines to meet at the hilum. 



The degree of polarization is high. It is about the 

 same in every part of the grain and does not vary much 

 in different grains. It is slightly higher than that of the 

 grains of B. peduncularis. 



With selenite the quadrants are fairly clear-cut, un- 

 equal in size, and sometimes irregular in shape. The 

 colors are pure and bright, but the yellow is often much 

 encroached on by the red dividing lines. 



Iodine Reactions. — With 0.25 per cent Lugol's solu- 

 tion the grains at once color a deep blue-violet; ^vith 0.125 



per cent solution they color fairly and then deepen slowly. The reaction is deeper than that of the 

 grains of B. peduncularis. After heating until all the grains are completely gelatinized, the solution 

 is colored lightly and the grains very deeply with iodine. The grains are much swollen and dis- 

 torted, especially at the di.stal end. After boiling for 2 minutes the solution is deeply colored, but 

 the grain-residues much less deeply. With the addition of a very slight excess of iodine the capsules 

 color a violet, and the capsules generally contain some blue-reacting starch at the proximal end. 



Staining Reactions. — With gentian violet the grains stain at once very lightly, but at the end 

 of 30 minutes they are lightly colored, somewhat more than the grains of B. peduncularis. 



With safranin the grains stain very lightly at once and after 30 minutes the color is light and 

 about the same as the grains of B. peduncularis. 



Temperature Reaction. — The temperature of gelatinization is 64° to 65° C, mean 64.5°. 



Effects of Various Reagents.— With chloral hydrate-iodine a few of the smaller grains react in a 

 minute and about half are affected and a few gelatinized in 4 minutes. About three-fourths are 

 affected in 10 minutes, about half being fully darkened, and all fully gelatinized in 45 minutes. 

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



With chromic acid some grains begin to react in 20 seconds. The reaction is general in IJ^ 

 minutes and is over in 3 minutes. The reaction is the same qualitatively as that of the grains of 

 B. peduncularis. 



Curve of Reaction- Intensities of Starch of Brodieea lactea. 



