GENUS LEtrCOIXTM. 



651 



Qart No. 220. 



I GV T P 

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PA FC P S CI PA CA 

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GENUS LEUCOIUM. 



Leucoium, or Leucojum, includes 8 species of bulbous plants, natives of Central and Southern 

 Europe and the region of the Mediterranean, and popularly known as the snowflake. Starches 

 from 2 species were examined: L. cestivum Linn., the summer snowflake, and L. vernum, the spring 

 snowflake. 



STARCH OF LEUCOIUM .^SSTIVUM. (Plate 55, figs. 329 and 330. Chart 220.) 



Histological Characteristics.- — Inform the grains are almost wholly simple and are isolated, except 

 a small number which occur in small aggregates and in clumps of small grains. Both the compound 

 grains and the aggregates often consist of linearly arranged, rather small components which num- 

 ber 2 to 6, rarely as many as 13. Pressure facets are occasionally found on the isolated grains. The 

 grains, as a rule, are somewhat irregular, irregularities being due chiefly to an abrupt depression at 

 one side of the proximal end, so that the contours of the two sides are different; to a protuberance at 

 or near the proximal end; or to slightly concave depressions (probably in some instances a point of 

 attachment for small grains) at varying points on the surface of a large grain. The conspicuous 

 forms are the irregular ovoid, nearly round, oval, elliptical, bean-shaped, mussel-shell-shaped to 

 clam-shell-shaped, pjTiform, and lenticular. The grains are usually flattened, and when seen on 

 edge are narrower at the distal than at the proximal end. 



The hilum is eccentric about one-third to one-fourth of the longitudinal axis. It may appear as 

 a clear round or lenticular spot, but usually it is fissured. In the broadened grains the clefts are 

 generally so arranged as to form a Y, T, or cross, or thorn-shaped figure. The clefts are deep, and 

 frequently ragged. 



The lamellcB are not very distinct, except one that is very refractive and located at varying dis- 

 tances from the hilum. They are less clearly demonstrable around the hilum and also sometimes near 

 the distal end, and in grains with an unfissured hilum they 

 may be observed directly around the hilum, as fine circu- 

 lar rings, but a short distance out they follow the outline 

 of the grain. On the medium-sized and large grains 24 

 can often be counted, rarely 30 to 36. 



The grains vary in size; the small ones are 3 by 2/*; 

 the large, broadened forms are 44 by 50/:, and the elon- 

 gated forms are 60 by 56/i in length and breadth. The 

 common size is about 30 by 38/i in length and breadth. 



Polariscopic Properties. — The figure is usually eccen- 

 tric and fairly distinct. Its lines are rather broad and 

 intersect obliquely; they may be straight, but are fre- 

 quently bent or bisected. Double and multiple figures, 

 both of the compound and aggregate type, are found. 



The degree of polarization is high, ranging from fair 

 to very high. Variation is frequent in the same aspect of 

 a given grain. 



With selenite the quadrants are fairly clear-cut, usu- 

 ally irregular in shape, and unequal in size. The blue 

 is generally pure, the yellow not quite pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color a rather deep violet 

 with a reddish tint, some deeper than others, the color deepening rapidly; with 0.125 per cent 

 solution the grains are colored a rather light violet with a reddish tint, the color deepening rapidly. 

 After heating the grains in water until they are completely gelatinized and then adding iodine, the 

 solution colors a deep indigo-blue and the grains a rather light bright blue, some darker than others. 

 If the grains are then boiled for 2 minutes and treated with iodine, the solution colors a very deep 

 blue and the grain-residues a light to fairly deep blue, while the capsules take on a violet color. 

 With an excess of iodine the grain-residues color a deeper blue, many with a reddish tint, and the 

 capsules become a deep heliotrope to a dull wine-red color. 



Staining Reactions. — With gentian violet the grains begin immediately to stain very slightly 

 and in 30 minutes are very lightly colored. 



With safranin the grains begin to stain slightly at once and in 30 minutes are lightly colored. 



Curve of Reaction'Intensitiefl of Starch of 

 Leucoium testivum. 



