748 



STARCHES OF IRIDACE^. 



vinequal in size, but the proportion of grains in which they are regular and equal is greater than in 

 C. stisianns (Cloth-of-Gold), but the degree of purity of the colors and the variation in the different 

 quadrants are the same. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color a fairly deep to light 

 reddish-violet, the fairly deeply colored grains become quite deeply colored in IJ^ minutes, while 

 the lightly colored grains deepen very slightly even in 5 minutes. If the grains are repeatedly 

 treated for 10 minutes by drawing the solution at intervals under the cover-glass, a number of grains 

 Btill remain with only a slight trace of color, but there is nothing in the microscopic structure, as 

 far as could be discerned, to indicate the cause for this resistance to iodine. A very thin layer of 

 starch was used in this reaction. With 0.125 per cent 

 solution about half the grains color a very light red- 

 violet, which in 3 minutes deepens slightly. Even when 

 treated for 15 minutes with the same solution, quite a 

 niunber of the grains are barely colored, while others vary 

 from a light red-violet to a deep heliotrope. The grains 

 color much more imevenly, less deeply on the whole, and 

 much redder in tint than in C. susianics (Cloth-of-Gold). 



Staining Reactions. — With gentian violet and with 

 safranin the grains begin to stain at once and in 30 min- 

 utes are lightly to fairly stained, the color being deeper 

 at the facets. There is a greater variation in the depth 

 of tint in the different grains, and some are stained deeper 

 than in C. Siisianus (Cloth-of-Gold). 



Temperature Reaction. — The temperature of gelatin- 

 ization is 71° to 73° C, mean 74°, 



Effects of Various Reagents. — With chloral hydrate- 

 iodine reaction begins at once. A few grains are gelatin- 

 ized in 40 seconds, nearly all in 3 minutes, and all but 

 rare resistant grains in 4 minutes. The reaction is com- 

 plete in 11 minutes. The isolated grains, as well as aggregates of regular outline, are the most 

 resistant. The reaction is qualitatively the same as in C. sv^anv^ (Cloth-of-Gold). 



The reaction begins at once with chromic acid. A few grains are gelatinized in 30 seconds, nearly 

 all in 45 seconds, all but rare resistant grains in 13^ minutes, and all in 2J^ minutes. The most 

 resistant grains are those with regular outline. The reaction is qualitatively the same as in C. 

 msianus (Cloth-of-Gold), 



Reaction begins at once with pyrogallic add. A few grains are gelatinized in 15 seconds, nearly 

 all in 30 seconds, and all in 50 seconds. The gelatinized grains are swollen and somewhat distorted, 

 but retain the general shape of the untreated grain. The reaction is qualitatively the same as in 

 C susianu^ (Cloth-of-Gold). 



The reaction begins at once with ferric chloride. A few grains are gelatinized in 1 J^ minutes and 

 practically all are in the process in 5 minutes. About nine-tenths are gelatinized in 10 minutes 

 and all but rare resistant grains in 15 minutes. The reaction is complete in 18 minutes. The re- 

 action is qualitatively the same as C. susianv^ (Cloth-of-Gold). 



The reaction begins immediately with Purdy's solution. A few grains are gelatinized in IJ^ 

 minutes and all are in various stages of the reaction in 5 minutes. About half are gelatinized in 

 15 minutes and two-thirds in 30 minutes. The grains with regular outline are the more resistant 

 to the reagent. The reaction is qualitatively the same as in C. susianus (Cloth-of-Gold). 



MINUTES 



Curve of Reaction-InteiuitieA of Starch of Crocus 

 var. (Baron von Brunow). 



Differentiation of Certain Starches of the Genus Crocus. 

 HiSTOLOoicAi, Chabactebibtics. Histological Characteristics. — Continued. 



Conspicuous Forms. 



C. tutianus (Clothrof-Gold): Simple, aggregates, well- 

 marked pressure facets very common, surface of 

 many of the grains irregular. Conspicuous forms 

 polygonal, dome-shaped with flattened or pointed 

 distal end, round or nearly round. 



Conspicuous Forms. — Continued. 



C. versicolor (filolh-ofSilver): Essentially the same as in C. 

 susianus (Cloth-of-Grold) , but the proportion of dome- 

 shaped, round, nearly round, and ellipsoidal grains 

 is much greater; the grains more regular in outline; 

 and the proportion of doublets and triplets greater. 



