GENUS CYCAS. 893 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains are colored immediately 

 and deeply a bluish-violet; with 0.125 per cent solution the grains tint quickly and the color deepens 

 rapidly. After heating the grains in water until all are completely gelatinized, the solution colors 

 very slightly with iodine, but the grains color a dark blue. The grains are very much swollen and 

 distorted. After boiling for 2 minutes the solution colors deeply, but the grain-residues less deeply 

 to but slightly. The capsules are colored blue-violet and are much folded, crumpled, and otherwise 

 distorted. 



Staining Reactions. — ^With gentian violet the grains begin to stain in 3 to 4 minutes and in 30 

 minutes are deeply stained a dark, dull violet. 



With safranin the grains begin to stain very slightly in 4 minutes and in 30 minutes the color 

 is not much deeper. 



Temperature Reaction. — The temperature of gelatinization is 73° to 74° C, mean 72.5°. 



Effects of Various Reagents. — ^With chloral hydrate-iodine the reaction begins in the smaller 

 grains in a minute, in the larger grains in 3 or 4 minutes, and is complete in three-fourths of the 

 grains in 45 minutes. The hilum becomes prominent. One of the central lamellae stands out as a 

 ridge. The grain begins to darken first at the angles of the facets and then all around the margin; 

 or less commonly irregular points on the margin darken increasingly, the darkening spreading and 

 later joining. This process usually extends inward evenly. The hilum swells last. The gelatinized 

 grains so formed consist of a dark, very distinct marginal ring inclosing a hghter inner portion. 

 They are not very large, and while somewhat distorted by protrusion of the parts first affected, 

 much of the original shape of the grain is retained. 



Reaction with chromic acid begins in 30 seconds and is completed in 5 minutes. The hilum 

 becomes prominent as a dark spot or bubble, and the lamellae are not increased in distinctness. 

 Fine striae radiating from the hilum appear throughout the grain; the hilum begins to swell and 

 the striae grow coarser and more distinct. The outer part of the grain is pushed outward to form 

 a thick ring, which is radially striated and has alternate refractive and non-refractive bands. The 

 band, as a whole, becomes much clearer and thinner, then dissolves at one place, and the inclosed 

 liquefied starch flows out and then the rest of the ring dissolves rapidly. Often at one point this 

 marginal band will be much thinner than at any other and dissolve more rapidly than the marginal 

 parts generally of this and other grains. 



The reaction with pyrogallic acid begins slightly in IJ/^ minutes and all but a few grains are 

 completely gelatinized in 30 minutes. Both hilum and lamellae are rendered more distinct than 

 normal. The grains which react quickly show fine striae radiating from the hilum. The hilum swells, 

 while at the same time the base of the grain, especially at the angles of the facets, is invaded by large 

 fissures, which portions of the grain swell out coincidently with the swelling of the hilum. In the 

 proximal part of the grain the unaffected portion at the margin is formed into a striated band, 

 which becomes thinner and more transparent, and finally forms a thin, homogeneous coating around 

 the gelatinized inner part of the grain. In grains which react more slowly, the hilum swells and the 

 rest of the grain is divided by fine radial striae which extend from the hilimi. A marginal ring is 

 formed of the more resistant starch and this gelatinizes finally, the whole grain then becomings 

 gelatinous mass. At times there are two distinct parts of this marginal ring, both of which are 

 finely striated and divided by a clear space or ridge which appears to occupy the same position as 

 the prominent lamellae noted in the normal grain. The gelatinized grains so produced are large 

 and somewhat distorted, especially at the base, but retain much of the original form. 



Reaction with ferric chloride begins in some grains in 3 minutes and is over in all in 25 minutes. 

 The hilum is usually rendered very distinct as a dark spot or bubble. None of the lamellae is visible 

 except the one especially prominent about midway between the hilum and margin. The marginal 

 starch becomes clear and darker; the inner portion of the grain, which is very much contracted, 

 is opaque and light in color. In most grains practically all parts gelatinize at the same time, but in 

 some grains the central part reacts first and the margin later. The gelatinized grains are large, 

 but not greatly folded or otherwise distorted. 



With Purdy's solution a very few grains show reaction in 7 minutes. Only a few grams are at 

 all affected, but some are completely gelatinized in 3 hours. The hilum and lamellae become very 

 distinct in all the grains. In the very few grains which gelatinize completely, the process consists 

 in the division of the grain by fine radial striae, swelling of the hilum, and the gelatinization of the 

 inner portion first, and the formation of a striated, ringed, marginal band with alternate refractive 



