GENUS GELASINE. 



765 



Polariscopic Properties. The figure is eccentric, distinct, and fairly clear-cut. Its lines tend 

 to be somewhat broad, and often broader and dimmer in some parts of their length. They are not 

 infrequently bent somewhat. 



_ The degree of polarization is fair to fairly high. It is very low or absent in some parts of the 

 grains and varies somewhat in different grains. It is high when the grain is viewed from the end 

 or sides. 



Ayith seleniie the quadrants are well defined, somewhat irregular in shape, and unequal in size. 

 The colors are not pure, except when the grains are viewed from the end or sides. 



Iodine Reactio7is.~With 0.25 per cent Lugol's solution the grains are colored at once and fairly 

 deeply; with 0.125 per cent solution they color lightly at first, but the color deepens quickly. After 

 heating until the grains are completely gelatinized, the solution is colored lightly and the grains 

 very deeply on the addition of iodine. After boiling for 

 2 minutes the solution is colored deeply and the grain- 

 residues hghtly. Almost all the capsules retain blue- 

 reacting starch, and all have a violet color after being 

 subjected to an excess of iodine. 



Staining Reactions. With gentian violet the grains 

 begin to stain lightly at once, but in 30 minutes the color 

 is not much deeper than at first. 



With safranin the grains begin to stain very lightly 

 in a minute and after 30 minutes the stain is still very 

 light. 



Temperature Reaction. The temperature of gelatin- 

 ization is 73 to 74 C, mean 73.5. 



Effects of Various Reagents. With chloral hydrate- 

 iodine reaction begins in some grains in Iji minutes, 

 about three-fourths are fully darkened and swollen in 30 

 minutes, and five-sixths in an hour. There is no further 

 change. The reaction may begin at the margin, at the 

 distal end, at one side, or at the proximal end. It then 

 spreads along the margin only as far as the two promi- 

 nences on the sides of the proximal end, and then inward over the whole grain. This process is 

 usually accompanied by some swelling. There is a fairly sharp line of demarcation between the 

 gelatinized and non-gelatinized parts of the grain. The hilum is often unaffected until all other 

 parts of the grain are altered. The gelatinized grains are fairly large, but not much distorted, and 

 they retain somewhat their original shape. They are usually uniformly a dark blue. 



With chromic acid the grains begin to react in 20 seconds and the reaction is practically over in 

 12 minutes. The hilum begins to swell somewhat. The grain becomes divided by fine radial striae, 

 which later grow very coarse. The inner portion passes into a gelatinous mass. There is formed 

 at the margin a striated ring, ragged on the inner edge, and showing at first very distinct, concentric, 

 alternate refractive and non-refractive bands. This ring becomes thinner, transparent, and quite 

 homogeneous as the grain swells. The end finally dissolves, allowing the inner, granular gelatinized 

 starch to exude and to pass into solution. Other parts of the capsule dissolve slowly. 



With pyrogallic acid some grains show slight reaction in 3 minutes. About five-sixths are affected 

 and a few are fully gelatinized in 60 minutes. Both hilum and lamellae are distinct. The hilum swells 

 and the grain becomes divided by fine radial striee. The inner portion is changed into a gelatinous 

 mass. A striated ring is formed at the margin, the inner part of which is very ragged. As the grain 

 swells this ring becomes thinner and more transparent. The gelatinized grains so formed are fairly 

 large and somewhat infolded and wrinkled, but they retain somewhat the original form of the grain. 



With ferric chloride a few of the smaller grains react in 2>^ minutes. About half are affected 

 and fully or partially gelatinized in 10 minutes, and three-fourths are gelatinized in 45 minutes. 

 There is not much further change. The reaction consists in the swelling of the hilum, the appear- 

 ance of fine striae which radiate throughout the grain, and the conversion of the inner portion into a 

 gelatinous mass. The material at the margin forms into a ring which is distinctly striated. As 

 the grain swells this ring becomes thirmer and transparent. The gelatinized grains are very large, 

 somewhat folded, and wrinkled. 



Curve of Reaction-Intensities of Starch of Gelasine 

 azurea. 



