618 STAKCHES OF CONVALLAMACE^. 



border is formed which has a liistrous appearance and is more transparent than the central part 

 of the grain. In the ovoid forms gelatinization begins at the distal end, while in the broadly tri- 

 angular or the somewhat mussel-shell-shaped grains it begins at one or both corners of the distal 

 end. The reaction advances towards the proximal end, at which point the resistant starch is gen- 

 erally broken into rather large granules, which later are gelatinized. The gelatinized grains are 

 swollen and distorted. 



The reaction with Purdy's solution begins immediately. A few small grains are gelatinized 

 in 30 seconds, a small number in a minute, about three-fifths in 2 minutes, and all but rare resistant 

 grains in 3 minutes. A few large grains are gelatinized in 10 minutes and several in 30 minutes. 

 The reaction is incomplete in an hour, and in most of the grains it has not proceeded further 

 than the swelUng of the hilum or fissures located at this point, the formation of branched fissures, 

 and sharper definition and striation of the lamellse. The hilum of the small grains swells, accom- 

 panied by gelatinization of the entire grain. The process is so rapid and the grains so small that 

 the details of the reaction can not be accurately noted. The cleft or the cavity located at the hilum 

 in the large grains swells and bubbles appear; branches are given off from the larger fissures which 

 penetrate all parts of the grain. The lamellae are rendered more distinct and become striated. As 

 gelatinization proceeds the starch is often broken into large granules which gradually pass into 

 gelatinization. In some of the broadly triangular grains gelatinization first takes place along the 

 coarser and more refractive lamellse, which thus forms a sharp line of demarcation between the 

 outer and inner part of the grain. In such grains gelatinization frequently does not proceed in 

 other parts of the grain beyond the initial steps noted. In both small and large gelatinized grains 

 a heavy capsular wall remains, so that while they are swollen they retain the general shape of the 

 untreated grain. 



GENUS TRILUUM. 



This genus comprises about 18 species, a dozen of which are natives of North America. The 

 American species are found from Canada and Nova Scotia to Florida, and as far westward as the 

 middle west, and 2 species are represented in California and British Columbia. The Asiatic species 

 are found from the Himalayas to Japan. The Trilliums are popularly known as wake robin, white 

 wood lily, ground lilj, and birthroot. Starches were obtained from T. grandiflorum Salisb. {T. 

 erythrocarpum) of Eastern America; T. ovatum Pursh., the Pacific Coast representative of the former 

 and much like it; and T. sessile var. califomicum Wats. (T. var. giganleum Torr.). The first two 

 are well-marked species. 



STARCH OF TRILLIUM GRANDIFLORUM. (Plate 50, figs. 297 and 298. Chart 202.) 



Histological Characteristics. — In form the grains are simple and isolated, with the exception of a 

 very few small aggregates and a few clumps that are readily separated. No pressure facets were 

 observed on the isolated grains. The surface is usually smooth, but somewhat irregular in outline, 

 owing to irregular development, causing many small depressions and elevations of the surface. 

 The conspicuous forms are the oval to ovoid and round. There are also pyriform, elliptical, reni- 

 form, lenticular, and irregular shapes. The grains generally are not quite so thick as broad, and 

 some of them are about two-thirds as thick as broad. 



The hilum is not distinct in most grains, and when it can be seen it appears as a round 

 or lenticular, large spot, usually eccentric about two-fifths or less of the longitudinal axis, and 

 in or slightly to one side of the median line. It is occasionally fissured, the fissure being single, 

 short, and indistinct. 



The lamMla are invisible. 



The grains vary in size from 2 to 16/i. The common size is 12/t. 



Polariscopic Properties. — The figure is usually eccentric, fairly distinct, and generally clear-cut. 

 The lines are rather thick and in some grains they become thicker and less clearly outlined as they 

 are nearer the margin. They are not bent. 



The degree of polarization is fair. It varies in different grains, the larger being the more polar- 

 iscopic, but it does not vary much in different aspects of the grains. 



With selenite the quadrants are well defined, usually fairly regular in shape, but unequal in 

 size. The colors are not pure. 



