GENUS ACONITUM. 



859 



STARCHES OF DELPHINACE.^. 



Class, Dicotyledones. Order, Ranales. Family, Delphinaceae. 



represented, Aconitura. 



GENUS ACONITUM. 



Genus 



The genus Aconitum includes from 18 to 80 species, according to different authorities. Aconite 

 is a native of temperate Europe, Asia, and North America, and is cultivated as an ornamental plant 

 in both Europe and America, chiefly in the former. Starch was prepared from the tuberous roots of 

 A. napellus Linn. {A. tauricum Jacq., A. pyramidale Mill.), the true monkshood or wolfbane, which 

 yields a powerful poison, and is officinal. 



STARCH OF ACONITUM NAPELLUS. (Plate 95, figs. 567 and 568. Chart 373.) 



Histological Characteristics. — In form the grains are simple, no compounds being observed, 

 but many aggregates and clumps. Many grains show one or more well-marked pressure facets; 

 the surface of the grains is frequently irregular because of the pressure facets. The conspicuous 

 forms are round and broadly ovoid, dome-shaped to hemispherical with one or two pressure facets; 

 also pyriform, triangular with well-rounded angles, polygonal due to many pressure facets, and 

 various indefinite forms. Many grains have the appearance of concave disks. 



The hilu7n is not always visible, but when seen it is a round or oval spot, not very refractive. 

 It may, even in the round forms, be eccentric from two-fifths to one-third of the longitudinal axis, 

 but in most grains it is eccentric not more than two-fifths. A depression is sometimes found running 

 through the grain just below the hilum. Fissures rarely 

 occur, but occasionally 3 short ones are found at the 

 hilum in the form of a Y. 



The lainellce are not demonstrable. 



The grains vary in size; the larger are 12 by I2ix, or 

 12 by Hjj. in length and breadth; the smaller 1 by l/x. 

 The common size is 7^. 



Polariscopic Properties. — The figure is usually more 

 or less eccentric. Its lines are rather thick and straight 

 in many forms, while in others they are bent or indistinct. 



The degree of polarization is low. It varies some- 

 what in different grains and also sometimes in the same 

 aspect of one grain. 



With selenite the quadrants are usually fairly well 

 defined, usually fairly regular in shape, but unequal in 

 size. The colors are fairly pure. 



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

 tion the grains all color a very deep blue- violet; with 0.125 

 per cent solution they color fairly deeply and the color 

 deepens rapidly. After heating in water until the grains 

 are completely gelatinized, the solution colors fairly and the gelatinized grains very deeply on the 

 addition of iodine. After boiling for 2 minutes the solution colors very deeply and some of the 

 grain-residues lightly or not at all. The capsules all color a violet with an excess of iodine. 



Staining Reactions. — With gentian violet and with safranin the grains begin to stain very lightly 

 at once and in 30 minutes they are only lightly stained. 



Temperature Reaction. — The temperature of gelatinization is 52° to 53.5° C, mean 52.75°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in 10 seconds and is 

 over in a minute. It begins at the distal end, which darkens first; then the starch at this point swells 

 out and the process of darkening and swelling moves upward and inward over the rest of the grain. 

 At times it affects all of the marginal region before that of the central portion. As the hilum is 

 approached a bubble forms there which increases in size as the grain swells, more perpendicularly 



Curve of Reaction-Intensities of Starch ol Aconitum 

 napellua. 



