880 



STAECHES OF PRIMtTLACE^. 



outer and more resistant parts of the grain are transformed into a thick, homogeneous ring which 

 becomes gradually thinner and clearer as the grain continues to swell. Soon a line of invagination 

 advances from the proximal end longitudinally along the whole length of the grain. The marginal 

 ring finally disappears. The gelatinized grains are large and ovoid and usually deeply wrinkled in 

 two or three places, 



STARCH OF CYCLAMEN COUM. (Plate 99, figs. 591 and 592. Chart 388.) 



Histological Characteristics. — In form the grains are usually simple. There are a few compound 

 grains and occasional aggregates of small grains which consist of two, three, or four components. 

 There are no clumps and but few grains with pressure facets. The surface of the grains is quite 

 smooth, nipple-Uke processes being very uncommon, and the grains are markedly more regular than 

 in C. repandum. The conspicuous forms are ovoid, oval frequently having the distal end pointed 

 or flattened and a hole or depression, and round or nearly round. There are also pyriform, dome- 

 shaped to hemispherical, angular with rounded corners, elliptical, and various indefinite forms. 

 The grains are more regular in outline, there are fewer nipple-like processes, and a greater tendency 

 to the ovoid and round types than in C. repandum. The grains are not flattened in any diameter. 



The hilum is not very distinct, and is a small, round, non-refractive spot, eccentric about 

 one-third to one-fourth of the longitudinal axis of the grain. There are rarely double hila, but 

 never more than 2, and the hilum is never fissured. When there are 2 hila they are very close to 

 one another, and never are separated by a fissure. 



The lamellm are usually distinct. Many grains ap- 

 pear to be surrounded by secondary deposits which do 

 not show a lamellar structure. The lamellae are fine and 

 generally regular and are more distinct near the hilum. 

 There appears to be a certain waviness and irregularity 

 in some of them which do not correspond with irregu- 

 larities of the margin, but are less marked than in C. 

 repandum, and there is no division of the lamellae into 

 two distinct sets or systems as in C. repandum. There 

 were about 20 lamellae on the larger grains. 



The grains vary in size from 4 to 36/i. The com- 

 mon size is about 18fi. 



Polariscopic Properties. — The figure is eccentric and 

 very distinct. The four lines are more or less visible in 

 whole or in part and are well defined and become broader 

 at the margin of the grain. They are straight or slightly 

 ciu-ved, as a rule, in marked contrast with the commonly 

 markedly irregular lines of C. repandum. 



The degree of polarization is high. It varies in different grains, in different aspects of the same 

 grain, and sometimes in the same aspect of a given grain. It is not so high as in C. repandum. 



With selenite the quadrants are well defined, irregular in shape, and unequal in size. The 

 colors are pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains tint immediately and deeply 

 blue-violet; with 0.125 per cent solution they tint lightly at once and the color deepens rapidly. 

 The color is slightly deeper than that of the grains of C. repandum. After heating until all the grains 

 are completely gelatinized, the solution is colored very slightly and the grains very deeply with 

 iodine. The grains are swollen, but not much wrinkled or distorted. After boiling for 2 minutes, 

 the solution is colored much more, but the grain-residues much less. All the grains have a violet 

 capsule. The grains are not so much disintegrated as those of C. repandum. 



Staining Reactions. — With gentian violet the reaction begins lightly at once and after 30 minutes 

 the grains are fairly deeply and evenly stained, slightly deeper than the grains of C. repandum. 



With safranin the reaction begins at once and after 30 minutes the grains are fairly and evenly 

 stained. The coloration is the same as C. repandum. 



Temperature Reaction. — ^The temperature of gelatinization is 56° to 57° C, mean 56.5°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in 13^ minutes and 

 la complete in 15 minutes. It is the same qualitatively as that of the grains of C. repandum. 



Curve of Reaction-Intensities of Starch of Cyclamen coum. 



