GENUS CANNA. 



801 



With /erne chloride the reaction begins in IJ^ minutes and is over in 25 minutes. It is the same 

 qualitatively as in C. warszewiczii. 



Reaction with Purdy's solution begins in 15 seconds and is over in the majority of grains in 

 2J^ minutes and in all in 6 minutes. It is qualitatively the same as in C. warszewiczii. 



STARCH OF CANNA EDULIS. (Plate 83, figa. 497 and 498. Chart 338.) 



Histological Characteristics. — In form the graias are simple with the exception of very rare 

 compounds in the form of two components. There are no aggregates or clumps and no pressure 

 facets. The surface of the grains tends to be quite smooth, the chief irregularities being in the form 

 usually of two depressions at the proximal end, causing the extreme end to be somewhat protrusive. 

 The most conspicuous form is the broad ovoid; there are also oval, clam-shell type, reniform, 

 pyriform, irregularly triangular and quadrangular with 

 rounded angles, nearly round forms, elliptical, and vari- 

 ous irregular forms. The broad ovoid grains are usu- 

 ally two-thirds to three-fourths as broad as long. From 

 the sides the grains are flat and one-fourth to one-third 

 as thick as broad, and have the shape of a long ellipse 

 with one end sometimes thicker than the other. On end 

 the grains are flattened and of an eUipsoidal form. 



The hilum is a very eccentric, not very distinct, 

 small, round, non-refractive spot, usually in the median 

 line, occasionally slightly to one side. It is never fis- 

 sured, and is occasionally double. 



The lameUcB are very distinct, and are coarse regu- 

 lar rings or arcs of circles which are probably continuous. 

 Those in the mesial part of the grain and at the distal 

 end are usually the coarser and more distinct. Occasion- 

 ally one or two near the hilum are very large and tend 

 to follow the outline of the margin, those most distal to 

 the hilum may be wavy in outline, otherwise they show 

 no irregularities. If there are two hila in one grain, there 



are two sets of lamellae, one corresponding to each hiliun, but they merge into one another a short 

 distance from the hila. The lamellae are a little less distinct and finer than in C. warszewiczii. 

 The number varies from 25 on the smaller grains to 85 on the larger; the common number is about 55. 



The grains vary in size from 15 to 120^. The common size is 60/*. 



Polariscopic Properties. — The figure is very eccentric, very well defined except at the margin 

 where the lines become broadened and somewhat hazy, and occasionally broken up and striated 

 with fine, white striae. Its lines are broad and usually two of the foiu- lines are observed throughout 

 their length running obliquely from the hilum. 



The degree of polarization is very high, about the same as that of C. roscoeana. Polarization 

 colors may be seen in some grains and are always visible when the grain is on end or edge. It is 

 higher than in the grains of C. warszewiczii, about the same as C. roscoeana. 



With selenite the quadrants are fairly sharply defined, fairly regular in shape, and unequal in 

 size. The colors are very pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color more deeply a blue- 

 violet, much deeper than C. warszmviczii and even deeper than C. roscoeana; with 0.125 percent 

 solution they color readily. After heating in water until the grains are completely gelatinized, the 

 solution colored a light indigo and the grains a deep indigo with iodine. After boiling for 2 minutes 

 the solution becomes a deep indigo color, but most of the grain-residues do not color at all. The 

 capsules, when excess of iodine is added, become a dark red-violet; they are generally much disin- 

 tegrated or reduced to granular masses. 



Staining Reactions. — With gentian violet the grains begin to stain at once and in 30 minutes 

 are deeply and evenly stained. The color is less than in the grains of C. warszewiczii. 



With safranin the grains begin to stain at once and after 30 minutes are fairly evenly and 

 deeply stained. The coloration is less than C. warszewiczii. 



Temperature Reaction. — The temperature of gelatinization is 67° to 68° C, mean 67.5°. 



Cunre of ReactJon-Intennties of Starch tii Canna eduUa. 



