GENUS LATHYRUS. 



397 



P I GV T 

 S 



aart No. 42. 



GV 5 T Cl CA PA FC P S CI P^ CA 

 ' ' PC PS 



5 1 



distinct; lines dividing the grains as well as the lamella; are more clearly defined; the striated border 

 appears more transparent and darker than the central opaque mass, and a clear line borders the 

 entire grain. An invagination occurs and the grain begins to swell at this point. In the rounded 

 forms this usually appears at one place, often followed later by swelling at one or more such invagi- 

 nated parts. In the bean-shaped grains the swelling frequently occurs at the depression on one 

 side of the grain and gradually spreads around the margin. During the process the gelatinized part 

 of the grains shows light lines of division, which frequently fly apart at these points, the segments 

 later breaking into pieces and becoming gelatinized. 



With Purdy's solution reaction begins in a few grains in 30 seconds and all are affected in 4 

 minutes. About one-third are gelatinized in 15 minutes and one-half in 30 minutes. There is very 

 little if any further change in an hour. The hilum in the round grains, if unfissured, swells and 

 becomes more distinct, and delicate radiating lines pass from it towards the margin. When 

 clefts are present at the hilum before the addition of the reagent, both clefts and refractive and 

 non-refractive lamellte become very sharply defined. The appearances of the phenomena of this 

 reaction are similar to those observed when the grains are treated with pyrogallic acid, but during 

 gelatinization the lamellae are more distinct, and as they are dissolved rows of bodies having a 

 crystalline appearance are more frequently observed. The remains of the lamellae are generally less 

 convoluted and the gelatinized grain more regular in shape than when treated with pyrogallic acid. 



STARCH OF LATHYRUS SYLVESTRIS. (Plate 7, figs. 41 and 42. Chart 42.) 



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

 allj' somewhat irregular. The grains are marked very irregularly by fissures which often appear to 

 border a non-lamellated space in the central part of the grain and separate it from the rest of the 

 grain. The conspicuous forms are the ovoid, oval, ellip- 

 soidal, and elliptical, with a few reniform, small, round 

 or nearly round grains, Avhich may be quite regular in 

 form, pyriform, and various modifications of the forego- 

 ing. The grains are usually not so thick as broad. 



The hila are so indistinct, even in the grains in which 

 the central portion is unfissured, that it is impossible to 

 determine anything definite about them. In some such 

 grains a number of faintly refractive granules may be 

 seen in the central, non-lamellated space. Many of the 

 grains have fissures extending through them in various 

 directions, but some have a single, long, clear-cut line 

 located mesiallj'. 



The lamellw are not verj' distinct, rather coarse, con- 

 tinuous bands which follow quite regularly the outline 

 of the grain. There are 10 or 12 on the larger grains. 



The grains vary in size from the smaller, which are 8 by 

 8yu, to the larger, which are 28 by 28// in length and breadth. 

 The common size is 24 by 19^ in length and breadth. 



Polariscopic Properties. The figure is centric or 

 slightly eccentric, distinct, and usually not clear-cut. In the unfissured or slightly fi.ssured, elongated 

 grains it consists of a single broad line extending along the longitudinal axis of the grain and divided 

 at each end into two lines. In rounded forms the figure is in the shape of a cross. The lines may be 

 curved, ragged, and otherwise distorted. 



The degree of polarization is low to fairly high, usually fairly high. It does not vary much in 

 different aspects of the same grain, but in the same aspect of some grains it is commonly lacking 

 centrally in a large area, and in others it is lower in different parts. It is lower than in L. odoratus 

 var. shahzada. 



With selenite the quadrants arc generally not well defined, irregular in shape, and unequal 

 in size. The colors are as a rule fairly pure. 



Iodine Reactions. With 0.25 per cent Lugol's solution the grains all color a fairly deep l)lue- 

 violet; with 0.125 per cent solution they stain rather lightly and the tint deepens rather rapidly. 

 The color is much deeper than in L. odoratus var. shahzada. After heating in water until all the grains 



il 



Curve of Reaction-Intensities of Starch of 

 Lathyrus sylvestris. 



