GENERA LENS AND LATHYRU3. 



395 



two or three rather large fragments, which are finally gelatinized. The gelatinized grains are so 

 much swollen and distorted that they do not retain the shape of the untreated grains. 



The reaction with Purdy's solution begins in a few grains in 2 minutes; about one-tenth are 

 gelatinized in 5 minutes, one-fifth in 15 minutes, one-third in 30 minutes, and one-half in an hour. 

 The hilum and the clefts enlarge, and the lamellae become sharply defined and striated. In the body 

 of the grain delicate fissures form which radiate from the clefts or the hilum. Gelatinization in 

 ellipsoidal grains that have mesial, elongated clefts often proceeds more rapidly towards one end of 

 the grain. As gelatinization progresses along the course of the radiating fissures, the lamellae are 

 often broken dovni in such a manner as to form a serrated lining to the capsule. During the solu- 

 tion of the lamellae, refractive bodies appear embedded in the gelatinized starch. If a mesial, elon- 

 gated cleft is not present in the untreated grain, a gelatinized area with embedded refractive bodies 

 is more quickly formed. The gelatinized grains, as a rule, are not much swollen, and the reaction 

 is chiefly limited to a central area which represents about one-third of the grain. A few grains, 

 possibly one-fiftieth, are swollen, and all the starch within the capsule is gelatinized, but no grains 

 in good condition were observed to reach this stage previous to the addition of the reagent. Since 

 several grains in the preparation are partially gelatinized, probably from the heat generated during 

 grinding, such a result may be reached only in these grains. 



GENUS LATHYRUS. 



Lathyrus is a genus of about 120 species, which are natives of the Northern Hemisphere and 

 South America; this includes both annuals and perennials, some of the latter being cultivated as 

 annuals. Both wild and cultivated forms are known as variously designated kinds of peas, the 

 most familiar being the sweet pea {Lathyrus odoratus Linn.) of common garden cultivation. The 

 starches of 4 species or their representatives were studied as types of the genus: L. odoratus var. 

 shahzada, the sweet pea, which is an annual and a native of Sicily; L. sylvestris Hort., the flat pea, 

 a perennial and a native of Europe; L. latifolius var. aZ6ws Hort., or everlasting pea, also a 

 perennial and a native of Europe; and L. magellanicus var. albus Hort., a perennial and a native 

 of the Straits of Magellan, and a maritime plant. 



STARCH OF LATHYRUS ODORATUS VAR. SHAHZADA. (Plate 7, figs. 39 and 40. Chart 41.) 



Histological Characteristics. — In form the grains are simple- and isolated. The surface is often 

 irregular, owing to depressions or rounded protuberances. The conspicuous forms are the ovoid, 

 ellipsoidal to elliptical, oval, reniform or bean-shaped, 

 and round; there are also irregularly quadrilateral, tri- 

 angular with rounded corners, and various modifica- 

 tions of the foregoing forms. The grains are usually 

 not so thick as broad. 



A central, rather indistinct hilum may be observed 

 in the unfissured, round, or rounded forms; in others may 

 be seen a number of small, granular, slightly refractive 

 bodies, whose exact number can not be determined. 

 Whether these represented hila is doubtful. Quite fre- 

 quently the grains are fissured and the fissure is usuall}^ 

 long, broad, and deep, extending through the middle of 

 the grain. It may be straight and clean-cut, but com- 

 monly is more or less ragged, and it may have very deep 

 branches extending out on each side almost to the mar- 

 gin. In some grains the fissuration is quite diffuse. 



The lamellce are very distinct, coarse, continuous 

 bands, which quite regularly follow the outline of the 

 grain. There are from 10 to 12 on the larger grains. 



The grains vary in size from the smaller ones, which 

 are 6 by 6^, to the larger, which are 38 by 25fj. in length and breadth. The common size is 25 by 

 20fi in length and breadth. 



Polariscopic Properties. — The figure is centric or slightly eccentric, distinct, but usually not 

 clear-cut. In the least fissured and in the unfissured grains there may be observed a cross or a 



PS CI PA CA 

 ~ PC PS 



of 



Reactioii'Intensities of Starch 

 odoratus var. shahzada. 



of 



MINUTES 

 Lathyrus 



