378 STARCHES OF LEGUMINOS^. 



STARCHES OF LEGUMINOS/E. 



Class, Dicotyledoues. Order, Resales. Family, Leguminosae. Genera represented : Vicia, 

 Phaseolus, Dolichos, Mucuna, Lens, Lathyrus, Pisum, Wistaria, Arachis. 



The Leguminosae, or pulse family, or legumes, are distributed over almost every country of 

 the earth, and include about 430 genera and 7,000 species, many of which are of considerable im- 

 portance, serving a great diversity of purposes. Of this large number of genera we had the oppor- 

 tunity of studying the starches of only nine representatives. 



GENUS VICIA. 



The genus Vicia is closely related to Phaseolus, Dolichos, Mucuna, and Glycine. Lens probably 

 serves as a connecting link between them and Lathyrus and Pisum. Vicia is stated to comprise about 

 200 species, of which about 120 are well defined. They are widely distributed in North and South 

 America and Europe, and to some extent in Central America. The starches of the following five 

 species in common cultivation were studied : Vicia saliva Linn, (spring vetch or tare) is cultivated 

 in lx)th the Old and New Worlds as a fodder crop or cover crop, or for its seeds, which are rich in 

 starch and yield a starchy flour, etc. V. villosa Roth, (sand, winter, or hairy vetch) is cultivated 

 chiefly as a cover crop. V. faba Linn. {Faha vulgaris Mcench., F. saliva Bernh.) is gro^vn for forage 

 and for the seeds. This species has been cultivated since prehistoric times and is known as the field, 

 horse, broad, tick, and Windsor bean. V. fulgens Batt and V. gerardi Vill. arc garden species that 

 are cultivated for their pea-shaped flowers. 



According to the agriculturist the beans in common cultivation may be grouped in five classes : 

 (1) the broad bean, of which Vicia faba is the type, as instanced in the well-known English horse 

 bean above referred to; (2) the kidney bean (Phaseolus vulgaris), including the many varieties of 

 the string and snap beans of the garden and field; (3) the flat, kidney-shaped beans (Phaseolus 

 lunatus), which include the lima beans; (4) the small flattened or rounded beans of Dolichos, well 

 known as the velvet bean, asparagus bean, etc. ; (5) the small, pea-like beans of Glycine, and typi- 

 fied by the common soy or soja bean, which contains little or no starch. 



STARCH OF VICIA SATIVA. (Plate 4, figs. 19 and 20. Chart 31.) 



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

 a few in aggregates. The grains are most commonly bean-shaped, elongated oval, ovoid, lenticular 

 and broadly lenticular, pyriform, and round to nearly round. There are some polygonal with rounded 

 comers, and rarely triangular or heart-shaped. There are many irregularities of the surface in these 

 forms caused by bulgings and indentations. Most of them show also deep, branching cracks run- 

 ning along the median line. The central part of such a grain appears to be a more or less homo- 

 geneous mass. This part is surrounded by a lamellated portion which is often fissured radially. 

 Many of the grains in this preparation were partially gelatinized, owing probably to heat generated 

 during grinding. The grains are not as thick as broad. 



In some of the rounded forms a hilum may be observed in the form of a central clear, slightly 

 refractive spot; but in other of these grains, and in the elongated grains, the position of the hilum 

 is marked by a mesial fissure which often has branches which run to the sides and end. The central 

 mass, when not fissiu-ed, appears more or less finely granular and occupies a large area, and in some 

 grains is surrounded by a fissure. 



The lameUxB are very distinct. In some of the forms they are coarse, concentric rings, and in 

 others those adjacent to the central mass follow the irregularities of its margin, while the outer 

 rings tend to follow the irregularities of the margin of the grain. Those nearer the central part 

 are coarser and more prominent than those near the margin. They vary in number from four to 

 twelve. 



The grains vary in size from 6 to 42/^. The common size is 26/*. 



Polariscopic Properties. — The figure is variable in accordance with the shape of the grain and 

 other conditions. In most of the grains there is a central dark area from which four or more lines 

 radiat«. The presence of fissuration gives rise to more or less modification. In the imfissured grains 



