GENUS BABIANA. 



765 



QartNo. 301. 



tl.*6 



GENUS BABIANA. 



The babianas are natives of South Africa and number about 50 species. Very few species but 

 quite a number of horticultural varieties are in cultivation. The starchy corms are eaten by baboons, 

 hence the name of the genus; and the same part when roasted resembles chestnuts prepared in the 

 same way, and are used as food by the Hottentots. Starches of two horticultural varieties of 

 unknown parentage were used as sources of starch; B. var. (Violacea) and B. var. (Athraction). 



STARCH OF BABIANA VAR. (VIOLACEA). (Plate 78, figs. 465 and 466. Chart 301.) 



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

 number of aggregates, in the form of doublets and triplets which maj' consist of components of 

 equal or unequal size. The isolated grains have usually from one to three pressure facets at the 

 distal end. The surface of the grains is smooth and quite regular. In some grains secondary de- 

 posits appear to have been added to the facets and adjacent parts. The conspicuous forms are the 

 hemispherical with usually two to three facets at the base, and spherical; also forms ranging from 

 the spherical to oval and elliptical, and various polygonal forms due to multiple facets. The doublets 

 are usually elliptical or oval and the triplets are rounded triangular. The grains are not flattened, 

 and when seen on end are spherical. 



The hihim varies from indistinct to fairly distinct, and is a comparatively large round spot, 

 rarely a cavity, and usually very slightly eccentrically situated. The hilum is rarely fissured. In 

 some grains there are two lines extending from each side of this cavity to the corners of the facets. 

 There are sometimes 2 hila in a single isolated grain. 



The lamellae are as a rule not distinct, and are rather coarse, regular, continuous rings having 

 near the margin the form of the outline of the grain. The number could not be accurately estimated, 

 but there are probably about 5 to 6 on the larger grains. 



The grains vary in size; the smaller are 3 by 3^; the 

 larger are 20 by 20At and 18 by 20ix in length and breadth. 

 The common size is usually 14 by 14/i. 



Polariscopic Properties. — The figure is usually slightly 

 eccentric, distinct, and clear-cut, sometimes very sharply 

 clear-cut and regular. The lines may be broad or nar- 

 row, and may not be clearly defined. They are gener- 

 ally straight. 



The degree of polarization is low to high, usually fair. 

 It varies in different grains and in different aspects of 

 the same grain. 



With selenite the quadrants are usually well defined 

 and regular in shape, but usually unequal in size. The 

 colors are fairly pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solu- 

 tion the grains color a rather light bluish-violet and the 

 color deepens rapidly; with 0.125 per cent solution they 

 color lightly and the color deepens fairly rapidly. After 

 heating in water until the grains are completely gelatin- 

 ized, the solution colors lightly and the gelatinized grains very deeply on the addition of iodine. After 

 boiling for 2 minutes the solution colors very deeply and the grain-residues fairly. When an excess 

 of iodine is added the capsules become violet. 



Staining Reactions. — With gentian violet the grains begin to stain very lightly in IH minutes 

 and in 30 minutes some are stained lightly and others fairly well. 



With safranin the grains begin to stain at once lightly and in 30 minutes are fairly stained. 



Temperature Reaction. — The temperature of gelatinization is 79° to 81° C, mean 80°. 



Effects of Various Reagents. — With chloral hydrate-4odine reaction begins in 30 seconds. It is 

 over in four-fifths of the grains in 73^ minutes and in all in 20 minutes. The grains stain a light 

 violet, and then the corners and edges of the facets darken and swell slightly. From these points 

 this process extends around the margin and inwards. It advances more rapidly inwards from the 

 distal end. When the hilum is reached the whole grain swells, but not to a great size. The gelat- 



Curve of Reaction- Intensities of Starch of 

 Babiana var. (Violacea). 



