796 



STAECHES OF CANNACE^. 



and become more gelatinous until finally they disappear in the form of a homogeneous, gelatinous 

 mass. The gelatinized grains resulting from this reaction are large, irregularly lobulated at the 

 proximal end, and folded in an irregularly lamellated fashion at the distal end. 



The grains begin to react in 2 minutes with ferric chloride. About half are gelatinized in 5 

 minutes and all in 15 minutes. The hilum and lamellae become indistinct, and the margin becomes 

 darker and clearer than the rest of the grain. A small fissure appears in the neighborhood of the 

 hilum, and one or two secondary fissures may develop near this which widen greatly, permitting of 

 swelling and protrusion from one or more points on the margin, distending the capsule. Strise 

 radiating from the hilum may also develop. Following this there may be more or less irregular 

 fissuring and swelling of the whole grain. In some grains the margin reacts more rapidly than 

 the inner portion, which latter is therefore surrounded bj' an irregular, gelatinous ring. The reac- 

 tion now moves inward, and small portions of the grain-substance are broken off and gelatinized 

 separately imtil the whole grain is ultimately completely gelatinized. The gelatinized grains are 

 very large and irregular, folded and nodular at the proximal end, and rounded and lamellated at 

 the distal end. 



The reaction with Purdy's solution begins in a few seconds and is complete in 2 minutes. The 

 hilum and lamellae become more distinct. The hilum and one or two nearby points swell rapidly 

 and protrude, forming two or three irregular, finger-like projections. The gi-ain becomes covered by 

 fine striae which radiate from the hilum. Four or five of these striae become very deep fissures which, 

 as the grain swells, open out, dividing the grain-substance into pyramids with their bases at the distal 

 margin and the apexes towards the proximal end. These parts are repeatedly subdivided again and 

 finally are converted into a homogeneous gelatinous mass. In the grains that react very rapidly 

 this process does not appear. The hilum swells out and the rest of the grain-substance passes rapidly 

 into a gelatinous mass. The gelatinous grains are very large, lobulated and irregular at the proximal 

 end, and folded in lamellar fashion at the distal end. 



STARCH OF CANNA ROSCOEANA. (Plate 83, figs. 493 and 494. Chart 336.) 



Histological Characteristics — In form the grains are simple. No compound grains or aggre- 

 gates were observed, and no pressure facets were detected on any grains. The surface of the grains 

 tends to be quite regular, and when iriegularities of outline are noted they are usually at the proxi- 

 mal end and in the form of unilateral or bilateral depres- 

 sions. The most conspicuous forms are the broad ovoid 

 and clam-shell type. This form varies also in relative 

 length and breadth and in the relative size of the two 

 ends. The clam-shell type is not so well formed as in C. 

 warszewiczii. There are also reniform, long triangular, 

 quadrilateral, and various incidental forms. Seen from 

 the side, the grains are elliptical or ellipsoidal, and fre- 

 quently one end is thicker than the other, giving them 

 a prismatic form. 



The hilum is a relatively small, not very distinct, 

 round, refractive spot, situated very eccentrically. In 

 the ovoid, triangular, and related forms it is usually in 

 the median hne and at the narrow end. In the other 

 forms it may be to one side of the median line. Rarely 

 it is marked by a fissiu-e. 



The lamellcB are very distinct, alternately Hght and 

 dark, continuous, concentric rings or arcs of circles which 

 are very regular. In some cases the outer lamellae follow 

 some irregularities in the margin. The hilum is their 

 common center. They vary greatly in distinctness in the same grain, and somewhat in different 

 grains. They are slightly coarser and more distinct than in C. warszewiczii. There are about 45 

 on the larger grains. 



The grains vary in size from 13 to 88^. The common size is 60/u. Some of the larger ovoid 

 grains measure 88 by 55/i, and some of the larger clam-shell or reniform grains measure 35 by 55/i 

 in length and breadth. 



PS CI PA I 

 "" POPS 



Curve of Reaction-Intensities of Starch of Canna 

 roscoeana. 



