516 



STARCHES OF LILIACE^. 



STARCH OF CALOCHORTUS NITIDUS. (Plate 29, figs. 171 and 172. Chart 124.) 



Histoloffical Characteristics. — In form the grains are simple, isolated, and without pressure 

 facets. The surface is commonly irregular, owing usually to the addition of large amorphous 

 masses to the primary grain. There is frequently a nodular protuberance of the proximal end, 

 formed by indentations in the margin at each side, and these indentations may be so deep that the 

 grain has a trefoil shape. The tendency to this deformation of the grains is seen throughout Calo- 

 chortus, but is most conspicuous in C. nitidus and C. benthami. There may be further modification 

 by varying degrees of indentation and by a greater or less prominence (at the distal end) of lateral, 

 fan-like extensions. The most conspicuous form is the fan-shaped with a knob-like protrusion of 

 the proximal end. There are also blunt ellipsoidal grains which are either long and narrow, or short, 

 round, ovoid, few pyriform, triangular, and mussel-shell forms. The grains are somewhat flattened, 

 and most are narrower at the proximal end than at the other. 



The hilum is sometimes distinct to very distinct, and comparatively large, but in some grains 

 it is not apparent. When visible it is a round, non-refractive spot, eccentric to about one-fifth 

 of the longitudinal axis of the grain and located usually in the smaller end of the grain, and in or 

 near the median line. It rarely is fissvu-ed. Double hila were not observed. 



The lamellce, while indistinct, appear to be regular and continuous. At some distance from 

 the hilum they follow the outline of the grain. They are rather fine and some are more distinct 

 than others in the same grain and also in different grains. Those near the distal end are usually 

 the more distinct. In some grains the smaller size and 

 more clear-cut appearance of the lamellae about the hilum, 

 in contradistinction to the outer lamellae, suggest that 

 they were produced at different periods of growth. There 

 are about 12 to 14 lamellae on the larger grains. 



The grains vary in size from 3.5 to 30/i. The com- 

 mon size is 14/4. 



Polariscopic Properties. — The figure is eccentric, dis- 

 tinct, usually clear-cut, and often irregular. The lines of 

 some grains are broader and less distinctly outlined at the 

 margin than centrally. They are often bent and other- 

 wise distorted, and placed at varying angles. 



The degree of polarization is high, varying in differ- 

 ent grains and in different aspects of the same grain, but 

 usually about the same in a given aspect of a given grain. 



With selenite the quadrants are generally sharply 

 defined, irregular in shape, and unequal in size. The 

 colors are fairly pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solu- 

 tion the grains are colored very deeply blue-violet; with 

 0.125 per cent solution they color lightly at first and then deeply. After heating until all the grains 

 are completely gelatinized, the solution is colored fairly well and the grains very deeply on the 

 addition of iodine. After boiling for 2 minutes, the solution is colored deeply, but the grain- 

 residues much less deeply and many not at all. The capsules all color a pale violet when an excess 

 of iodine is added, and the proximal portions often contain some blue-reacting starch. 



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

 minutes they are fairly and evenly stained. 



With safranin the grains begin to stain at once and after 30 minutes they are fairly deeply, 

 but somewhat imevenly stained. 



Temperature Reaction. — The temperature of gelatinization is 54° to 55.5° C, mean 54.75°. 



Effects of Various Reagents. — ^With chloral hydrate-iodine the reaction begins in 15 seconds and is 

 complete in 2 minutes. It usually begins at both ends, the distal end being affected first and becom- 

 ing very dark and swollen, and then the proximal end. This process rapidly spreads to the central 

 portion, which quickly swells. The swollen grains are at first uniformly dark, but after 30 minutes 

 they show a light space at the proximal end and a dark, more or less homogeneous mass at the distal 

 end. It is not unusual for this mass to be crossed by light fissures. The gelatinized grains are 

 fairly large and quite regular in outline, and they retain somewhat the original form of the grain. 



Curve of Reaction-Intensities of Starch of 

 Calochortus nitidus. 



