842 



STARCHES OF NYMPH^ACEiB. 



begins to shrink and finally disappears. Finally, when the grain is fully gelatinized it consists of a 

 very thin, transparent capsule, much folded and crumpled, and inclosing a mass of semifluid starch. 

 The reaction with Purdy's solution begins in a few grains in 45 seconds and in about one-third 

 in 2 minutes. About two-fifths are nearly completely gelatinized in 15 minutes. The reaction, as 

 far as it goes, is qualitatively the same as that with pyrogallic acid. 



STARCH OF NYMPH^A MARLIACEA VAR. ALBIDA. (Plate 92, figs. 547 and 548. Chart 360.) 



Histological Characteristics. — In form the grains are simple. No compound grains were observed. 

 There are some small aggregates, generally in the form of doublets and triplets, and also a few clumps. 

 Pressure facets were noted on some grains. The surface of the grains is usually somewhat irregular, 

 owing to the same causes as noted under N. alba. The conspicuous forms are round, ovoid, and oval; 

 also elliptical, dome-shaped, hemispherical, angular with well-rounded angles, and various indefinite 

 forms. The grains are not flattened. They are somewhat more irregular than N. alba. 



The hilum is a fairly distinct, round, refractive spot, centric or nearly centric in the round forms, 

 and eccentric from very slightly to one-third, usually about two-fifths, of the longitudinal axis. 

 There are 2 hila in some grains. Fissures are fairly often found at the hilum ; they may be transverse, 

 diagonal, two short ones intersecting each other and form- 

 ing a cross, three meeting at one point, or two slightly 

 curved which proceed from a central point slightly nearer 

 the proximal end. 



The lamellas are indistinct in many grains, but if ob- 

 served they are seen to form fairly coarse rings around 

 the hilum; and when distinct throughout the grain they 

 tend to follow the outline of the margin. Frequently 

 one lamella, at from about one-fourth to one-half of the 

 distance between the hilum and the distal margin, is 

 more prominent than the others; secondary sets of lamel- 

 lae are not uncommon. The number was not determined. 



The grains vary in size; the smaller are 6 by 6/x; the 

 larger are 30 by 30ju or 28 by 24/i in length and breadth. 

 The common size is 19fi. 



Polariscopic Properties. — The figure is centric or 

 slightly eccentric. Its lines are rather thick and become 

 broader towards the margin. They are straight in many 

 grains, while in others they are bent and occasionally 

 bisected. The figure is essentially the same as in N. alba. 



The degree of polarization is fair to high. There are variations in different grains, in different 

 aspects of the same grain, and occasionally in the same aspect of a grain. It is higher than in A'^. alba. 



With selenite the quadrants are usually well defined, irregular in shape, and unequal in size. 

 The colors are usually pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains all color a fair blue-violet; 

 with 0.125 per cent solution they color lightly and the color does not deepen rapidly. It is slightly 

 less than that of the grains of N. alba. After heating in water until the grains are completely gelat- 

 inized, the solution colors lightly and the gelatinized grains very deeply on the addition of iodine. 

 After boiUng for 2 minutes, the solution colors very deeply and the grain-residues fairly. The cap- 

 sules all color a red-violet with an excess of iodine. 



Staining Reactions. — With gentian violet the grains begin to stain very lightly at once and in 30 

 minutes are rather lightly stained, the same as that of the grains of A^. alba. 



With safranin the grains begin to stain lightly at once and in 30 minutes are fairly stained. The 

 stain is sUghtly less than that of the grains of N. alba. 



Temperature Reaction. — The temperature of gelatinization is 67° to 69° C, mean 68°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in a minute. It is 

 over in half the grains in 15 minutes, in three-fourths in 50 minutes, and in all but a few in 1}^ hours. 

 It is the same qualitatively as that of the grains of N. alba. 



The reaction with chromic acid begins in 45 seconds and is over in 3J^ minutes. It is the same 

 qualitatively as that of the grains of N. alba. 



Curve of Reaction-Intensities of Starch of Nympha 

 marliacea var. albida. 



