Carnegie Institution of Washington Publication Volume 270, PT. 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ...then quickly at the proximal end, with swelling of the hilum, but in a moderate number of grains it begins first at the proximal end and then at the distal end. It progresses by but one method, and it is preceded by shallow indentations in the margin and a pitted appearance of the surface of the ungelatinized portions of the grain. It progresses regularly from either end of the grain, and the last part to be gelatinized is just distal to the hilum, being split, becoming widely separated, and gelatinizing independently of one another. The gelatinized grains are much swollen, have rather thick capsules, and are greatly distorted. They do not retain any resemblance to the form of the untreated grain. The reaction with chromic acid begins immediately. Complete gelatinization occurs in about 53 per cent of the entire number of grains and 82 per cent of the total starch in 3-minutes; in about 70 per cent of the grains and 90 per cent of the total starch in 5 minutes; in about 87 per cent of the grains and 97 per cent of the total starch in 15 minutes; in more than 99 per cent of the grains and total starch in 30 minutes. (Chart D 348.) The hilum becomes distinct in all the grains, attended by the formation of a bubble in but few grains. The lamellae are distinct. Gelatinization begins at the hilum, which swells rapidly, more rapidly in the direction of the proximal than the distal end. Two short fissures extend from the hilum on either side not more than half the distance toward the distal end, and the material included between them is distinctly and irregularly fissured. As gelatinization proceeds and the grain swells these fissures separate ofi spicules of starch which later become refractive granules and which later unite to form a very irregular granular mass...