756 



STARCHES OF IRIDACBiE. 



A few grains react in 10 seconds with Purdy's solution, but after 45 minutes only a few are even 

 partially gelatinized. There is no further change. The great majority never react. This reaction 

 is similar in character to that with pyrogallic acid. 



GENUS SPARAXIS. 



Sparaxis is a genus of less than half a dozen species of bulbous plants, closely related to Ixia. 

 It is a native of South Africa, and popularly known as the wand flower, or rarely as the harlequin 

 flower. There are a number of garden varieties, chiefly in the form of hybrids, which for the most 

 part are referable to 3 species: S. bulbifera Ker., S. tricolor Ker., and S. grandifloi-a Ker. All of these 

 are also known as corresponding Ixias. Starches from two garden forms were prepared : <S. grandi- 

 flora alba and S. var. (Albertine). 



STARCH OF SPARAXIS GRANDIFLORA ALBA. (Plate 76, figs. 455 and 456. Chart 296.) 



Histological Characteristics. In form the grains are almost wholly simple. There are a few 

 compound grains consisting of few components. The simple grains are either isolated, in aggre- 

 gates of few components, or in clumps. Most of the isolated grains have sharply defined pressure 

 facets. The surface of the grains is sometimes irregular, owing chiefly to the flattening of one or 

 more points on the curved siu'face, or to the occasional presence of ridges found principally upon 

 the rounded forms. The conspicuous forms are dome-shaped, which sometimes have a pointed 

 base, hemispherical, round, and nearly round. There are also a few ovoid, pyriform, imperfect 

 quadrangular that are rounded with broadened and flattened distal end, broadly triangular with 

 curved base and rounded angles, and ellipsoidal with sometimes a slightly broadened and flattened 

 distal end. The aggregates are more often doublets of 

 ellipsoidal or almost spherical form; but triplets, quad- 

 ruplets, and even quintuplets with components arranged 

 compactly are frequently observed. Aggregates with 

 components in linear arrangement are also occasionally 

 present. 



The hilum may be noted as a clear round spot, cen- 

 tric or eccentric to about one-third to one-fourth of the 

 longitudinal axis. A small, irregular cavity, from which 

 two short fissures usually proceed, is often found in the 

 dome-shaped grains. A cavity with two or more fissures 

 is present in the rare pyriform and broadly triangular 

 grains. 



The lamellce are usually indistinct, but occasionally 7 

 fairly coarse, complete rings may be counted in the round 

 grains; 8 or 9 in the dome-shaped grains. The lamellae 

 immediately around the hilum are usually circular in out- 

 line, but the remaining ones tend to have the form of the 

 outline of the grain. On fair-sized dome-shaped grains 8 

 fairly coarse lamellae can sometimes be distinguished. 



The grains vary in size; the smaller are 3 by 2ix] the larger dome-shaped grains are 16 by 14/x 

 in length and breadth. There are a number of isolated, round grains, the larger of which are 16 

 by 16/i. The common size of the dome-shaped grains is 12 by 10^, and of the round grains 12 by 

 12/i in length and breadth. A few ellipsoidal grains are usually 20 by 16m, but rarely may be 30 

 by 24/i in length and breadth. 



Polariscopic Properties. The figure is slightly eccentric, centric, and quite eccentric. Its lines 

 are frequently not distinct throughout, and are often either bent or bisected. Double figures indicat- 

 ing the presence either of aggregates or compound grains, essentially the former, are fairly frequent. 



The degree of polarization is fair to high. There is a variation in the different grains, as well 

 as in the same aspect of a given grain. One or two quadrants may be much lower than others. 



With selenite the quadrants are usually not clearly defined, and are generally irregular in shape 

 and unequal in size. There is often a variation in the purity of the colors in a given grain; they may 

 be impure in one or more quadi-ants and pure in others. The yellow is more often impure than the 

 blue, which latter is pure in the greater number of grains. 



Curve of Reaction-Intensities of Starch of Sparaxis 

 graadiflora alba. 



