380 



STARCHES OF LEGUMINOS.B. 



CI PA CA 

 PC PS 



hilum and lamellse are very prominent. The reaction begins with gelatinization, great swelling 

 and protrusion at one end, and it advances slowly over the whole grain, proceeding more rapidly 

 in the central part. The reaction reaches the other end, at which point the grain may be divided 

 by fissures, and the pieces suddenly separate, and then undergo swelling independently. The 

 swollen grains are very large and irregular, and much distorted by lobulations. 



The reaction with Purdy's solution begins in some of the grains in 30 seconds. About three- 

 fourtlis are affected and about half are fully gelatinized in 15 minutes. The reaction is not complete 

 in an hour. Both hilum and lamellaj are very prominent. The character of the reaction is identical 

 wth that with pyrogallic acid, with the exception that very often the grains are not greatly swollen. 



STARCH OF VICIA VILLOSA. (Plate 4, figs. 21 and 22. Chart 32.) 



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

 a few found in some closely fitting aggregates. The surface of the grains is frequently rather irregu- 

 lar, owing either to incidental elevations or indentations at various points. The conspicuous forms 

 are the bean-shaped, elongated, irregular oval and regular oval, and small rounded forms. There 

 are some polygonal, triangular with rounded angles, and irregular heart-shaped grains. The grains 

 are usually not so thick as broad. 



In some of the small, simple, rounded forms the hilum appears to be round, and centric or 

 slightly centric, but in other rounded forms and in the bean-shaped and other larger forms, the 

 position of the hilum is represented by a fissm-e. The central non-lamellated portion of the grain 

 is frequently fissured. A conspicuous fissm-e, which is long, broad, and deep and extends along the 

 middle of the grain, is quite often observed. It may be clear-cut, but frequently is rather ragged, 

 and usually has branches extending on each side into the 

 substance of the grain almost to the margin. There is in 

 some grains a central granulated mass which may be sur- 

 rounded by a branched wreath-like fissure. 



In the round forms the lamellcE are distinct, rather 

 coarse, continuous, concentric lines. In many of the 

 elongated grains they are coarse, continuous bands, the 

 outermost following the outline of the margin, and there- 

 fore showing irregularities of the contour of the grain. In 

 some of the grains the lamellae are more distinct centrally 

 than peripherally, but in others the reverse. They vary 

 in nimiber from four to ten, and resemble those observed 

 in Vicia saliva. 



The grains vary in size from the smaller, which are 

 6 by 6ai, to the larger, which are 44 by 24ju in length and 

 breadth. The common sizes are 28 by 21/i or 30 by 26^ 

 in length and breadth. 



Polariscopic Properties. — The figure is centric or 

 slightly eccentric. In the majority of the grains there 

 is a large, central dark space from which several dark 



lines pass at irregular intervals. The lines of the figure of the small grains are rather thick, and 

 may be either straight or bisected. Peculiarities of the figures and lines, as a whole, are the same 

 as those observed in Vicia saliva. 



The degree of -polarization is high, although it is absent from a considerable space in the medial 

 part of most of the larger grains, and it sometimes varies in the same aspect of a grain. It is higher 

 when the grain is viewed from the side. It is scarcely as high, and the mesial non-illuminated area 

 is larger, than in Vicia saliva. 



With selenite the quadrants in some grains are well defined throughout, while in others they 

 are only distinct near the margin of the grain. They are usually irregular in shape and unequal in 

 size, and often subdivided. The colors are commonly pure and about the same as in Vicia saliva. 



Iodine Reactions. — With a 0.25 per cent Lugol's solution the grains are colored a fairly deep 

 violet; with a 0.125 per cent solution they color a very light violet, and the color deepens fairly 

 rapidly. The tint is deeper than in V. saliva. After heating in water until all the grains are gela- 

 tinized, the solution colors an indigo-blue and the gelatinized grains a blue-black on the addition of 



MtNUTES 

 Curve of Reaction-Intensities of Starch of Vicia vitlosa. 



