438 



STAECH OF SAPINDACE^. 



STARCH OF SAPINDACE/E. 



Class, Dicotyledones. Order, ^sculiuales. Family, Sapindaceae. Genus 



represented, ^Esculus. 



GENUS /ESCULUS. 



About a dozen species of the genus ^senilis are recorded, all said to be native to North America, 

 Eastern Asia, and the Himalayas to Northern Greece. ^'Esculus includes the well-known horse 

 chestnut or buckeye, which is cultivated extensively as a shade tree, and in some countries also 

 for the fruit or seed, which is used for food for sheep and other animals. The native American 

 species are represented chiefly by /E. octandra Marsh (the sweet buckeye), M. glabra Willd. (the 

 fetid buckeye), and xE. calif ornica, Nutt. The .starch used was obtained from the fruit of Ai. hippo- 

 caslanmn Linn., the common horse chestnut, which is native of the region from the Himalayas to 

 Northern Greece, but grown quite largely elsewhere. 



Chart No. 73. 



GV S T CI CA Pfl FC P S CI PA CA 

 PC PS 



6 1 



STARCH OF .ESCULUS HIPPOCASTANUM. (Plate 13, figs. 75 and 76. Chart 75.) 



Histological Characteristics. In form the grains are simple and isolated. The surface of the 

 grains is somewhat irregular, the irregularities being due to slight rounded elevations and depres- 

 sions and to small and large rounded prcjtuljerances from the margin. The distal end usually 

 appears thinner than the rest of the grain and sometimes is not lamellated. Tiie conspicuous forms 

 are the elongated oval, having a narrow, pointed, distal end, ellipsoidal, pyriform, and spherical or 

 nearly spherical. The grains are narrower at the distal than at the jiroximal end. 



The hilum is a fairly distinct, rather small round spot, sometimes centric in the lenticular 

 and spherical forms, but eccentric in most of these and in other forms. The eccentricitj'^ is commonly 

 one-third to one-fifth of the longitudinal diameter and is 

 usually about one-fourth. The hilum is sometimes fis- 

 sured, the fissure usually being single and in the form of 

 a straight but rather broad and irregular transverse cleft, 

 or a transverse line having a double curve resembling the 

 lines of the outstretched wings of a flying bird. Some- 

 times a longitudinal fissure extends from the hilum nearly 

 to the distal margin. 



The lamella; are fairly distinct in the large grains, but 

 indistinct in the medium to smaller grains ; they are rather 

 coarse, somewhat irregular, continuous bands, circular 

 near the hilum, but elsewhere tending to follow the out- 

 line of the margin. They often vary much in size in 

 different parts of the grain. There are about 20 on the 

 larger grains. 



The grains vary in size from the smaller, which are In, 

 to the larger, which are 32 by 16;u in length and breadth. 

 The common size is 20 by 12ju in length and lireadth. 



Polariscopic Properties. The figure is eccentric ex- 

 cept in some lenticular and spherical forms. It is fairly 

 distinct and usually fairly clear-cut. Frequently one or more lines composing it may not be visible 

 on account of the low or absent polarization in some parts of the grain. The lines are generally 

 curved and occasionally bisected. 



The degree of polarization is fair, varying somewhat in different grains, and is higher in the 

 same grain when viewed on end. It is low or absent in some parts of some grains. 



With selenite the quadrants are generally well defined, irregular in form, and unequal in size. 

 The colors, while not very bright, may be quite pure, though the yellow is often mixed with red. 



Iodine Reactio7)s. With 0.25 per cent Lugol's solution the grains are all colored a deep blue- 

 violet; with 0.125 per cent solution they are colored fairly, but the color does not deepen rapidly. 



Curve of Reaction-Intensities of Starch of i^sculus 

 hippocastanum. 



