GENUS CROCUS. 747 



regular outline are the most resistant. A dark ring or an irregular, looped structure appears at the 

 hilum in a much larger proportion of grains than in C. susianics (Cloth-of-Gold). The reaction is 

 qualitatively the same as in C susianus (Cloth-of-Gold). 



The reaction begins at once with chromic acid. A few grains are dissolved in 45 seconds, the 

 majority in 2 minutes, all but rare resistant grains in 2J^ minutes, and in all in 4 minutes. The grains 

 with reg\ilar outline are the most resistant. The reaction is qualitatively the same as in C. susianus 

 (Cloth-of-Gold). 



The reaction begins immediately with pyrogalUc acid. A few grains are gelatinized in 20 sec- 

 onds, the majority in 40 seconds, and all in 13^ minutes. A bubble is formed at the hilum much 

 more often than in C. susianus (Cloth-of-Gold), and the gelatinized grains are more regular in out- 

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



The reaction with ferric chloride begins in a few grains in a minute. A small number are gelat- 

 inized in 2 minutes, practically all are in various stages of gelatinization and about one-third are 

 gelatinized in 5 minutes, the majority are gelatinized in 7 minutes, and all but rare resistant grains in 

 15 minutes. The reaction is complete in all in 45 minutes. Bubbles collect at the hilum in a greater 

 proportion of grains than in C. susianus (Cloth-of-Gold). The most resistant grains are those with 

 regular outline and also those in which the cavity or cleft at the hilum swells very much, from which 

 bubbles are later expelled. In such grains the marginal border broadens, the lamellae become dis- 

 tinct and striated, and the starch is finally gelatinized without the distension of the capsule at one 

 or more points. The reaction is qualitatively the same as in C. susianus (Cloth-of-Gold). 



The reaction begins at once with Purdy's solution. A few of the smaller grains are gelatinized 

 in 2 minutes, and all are in various stages of the process in 5 minutes. About one-fifth are gelatin- 

 ized in 10 minutes, but there is little if any further progress at the end of 15 minutes. Gelatiniza- 

 tion has only proceeded as far as that in the grains of C. susianus (Cloth-of-Gold) in a very small 

 proportion of the grains, probably about one-fourth, at the end of 30 minutes. The hilum is swollen, 

 radiating fissures are formed, and the lamellae become distinct and striated. The reaction is quali- 

 tatively the same as in C. susianus (Cloth-of Gold). 



STARCH OF CROCUS VAR. (BARON VON BRUNOW). (Plate 75, figa. 445 and 446. Chart 291.) 



Histological Characteristics. In form the grains are simple. They are partly isolated, partly 

 in aggregates which consist of two or more components, and partly in clumps of many grains. Well- 

 marked pressure facets are found on most of the isolated grains. The irregularity frequently ob- 

 served on the surface of the grains is due to the causes noted in C. susianus (Cloth-of-Gold). The 

 conspicuous forms are polygonal, dome-shaped with flattened or pointed end, and round or nearly 

 round. Compared with C. susianus (Cloth-of-Gold), the proportion of dome-shaped and curvi- 

 linear grains is greater and the grains are more regular in outline. They are more irregular than 

 C. versicolor (Cloth-of-Silver). The aggregates are similar to those of C. susianus (Cloth-of-Gold), 

 but there aie more doublets, triplets, and quadruplets consisting of components of regular shape 

 and of equal size. 



The hilum is frequently observed as a round or lenticular spot, usually eccentric from slightly 

 to one-third of the longitudinal axis. The hilum is more often demonstrable and either the fissures 

 or cavity when present are deeper than in C. susianus (Cloth-of-Gold). 



The lamellcB are not usually demonstrable and the number can not be determined, since they are 

 not obvious throughout the grain. 



The grains vary in size; the smaller are 3 by 2ix; the larger are 18 by 16m in length and breadth. 

 The common size is 13 by 12,u in length and breadth. There are a number of large round or nearly 

 round grains which may be 18^, the common size being 12/t. 



Polariscopic Properties. The Jigiire is usually either slightly eccentric or centric. It is essen- 

 tially of the same character as that noted in C. susianus (Cloth-of-Gold), but more often distinct 

 and regular throughout the entire grain, though more irregular and less often distinct than in C. 

 versicolor (Cloth-of-Silver). Double and multiple figures are also observed. 



The degree of polarization is fair to high. The same variation is found in the different grains and 

 in one aspect of a given grain as noted for C. susianus (Cloth-of-Gold), and there are more grains in 

 which polarization is high throughout the grain, but not so many as in C. versicolor (Cloth-of-Silver). 



With selenite the quadrants are frequently not well defined, but they are clean-cut in a greater 

 proportion of grains than in C. susianus (Cloth-of-Gold). They are generally irregular in shape and 



