GENERA MORiEA AND HOMERIA. 



709 



Qart No. 268. 



of a secondary figure sometimes appear in such cases, and sometimes the central part of the figure 

 is made up of a large dark spot of irregular form. 



The degree of polarization is high. It varies with the position of the grain, in different grains, 

 and notably in different parts of the same grain. It is usually higher over the irregular accretions 

 on the surfaces. 



With selcnite the quadrants are clear-cut, often very irregular in shape, and rarely equal in 

 size. The colors in some are pure, but in others not. 



Iodine Reactions. With 0.2.5 per cent Lugol's solution the grains are colored deeply at once 

 and the color deepens rapidly; with 0.125 per cent solution they color at once almost as deeply as 

 with a 0.25 per cent solution. After heating in water 

 until the grains are completely gelatinized, the solution 

 is colored faintly and the grains very deeply on the addi- 

 tion of iodine. After boiling for 2 minutes the solution 

 colors much more deeply, but the grain-residues much 

 less. With slight excess of iodine the grain-residues 

 show a dark, blue-violet-colored wall. Practically all the 

 capsules retain more or less blue-reacting starch. 



Staining Reactions. With gentian violet and with 

 safranin the grains begin to stain very lightly at once, 

 but after 30 minutes they are only lightly stained. 



Temperature Reaction. The temperature of gelatin- 

 ization is 69 to 71 C, mean 70. 



Effects of Variotis Reagents. With chloral hydrate- 

 iodine the reaction begins in the smaller grains in 13^ 

 minutes. Some become gelatinized in 5 minutes, about 

 three-fourths in 45 minutes, and all in IJ2 to 2 hours. 

 The reaction begins at the proximal end, which darkens 

 and swells somewhat, and the process extends over the 

 grain. The line of demarcation between the gelatinized 

 and non-gelatinized portions is fairly well marked. The swollen grains are not very large, but 

 uniformly dark and somewhat irregular in form. 



With chromic acid some grains react in 20 seconds. The reaction is general in a minute and is over 

 in 4 minutes. The hilum becomes very prominent and then swells, and the grain becomes covered 

 by fine striae. The inner part passes into a gelatinous mass, while the outer forms a rather thin ring, 

 ragged on the inner side, which becomes thinner and transparent and finally dissolves at one end, 

 when the inner gelatinized starch flows out and is dissolved, followed by the solution of other parts. 



With pyrogallic acid a slight reaction occurs in some grains in 2 minutes; all are affected and 

 about one-fifth partially gelatinized in 8 minutes, and half are partially gelatinized in 45 minutes. 

 The hilum is very prominent, the lamella? fairly so. The hilum swells, the grain becomes covered by 

 fine striae, and the inner portion is changed into a gelatinous mass. The marginal ring is rather thin, 

 very distinctly striated, and ragged on the inner side. It grows fairly thin and transparent as the 

 grain swells. The grains are never completely gelatinized. 



The reaction with ferric chloride begins in some grains in 6 minutes. About half are gelatinous 

 in 20 minutes, almost all in 30 minutes, and all are gelatinized in 45 minutes. The hilum becomes 

 prominent and swells, and the inner part is altered into a gelatinous mass. The margin grows thin, 

 very distinctly striated, and very ragged on the inner edge. This ring becomes thinner and trans- 

 parent as the grain swells. The swollen grains are large, transparent, somewhat folded and wrinkled, 

 but are generally smooth and not greatly distorted. 



With Purdy's solution some grains are affected in 5 minutes and all are affected and a few 

 almost completely gelatinized in 30 minutes. This reaction, as far as it goes, is practically identical 

 with that to pyrogallic acid. 



GENUS HOMERIA. 



The genus Homeria comprises 6 species of bulbous plants, natives of the Cape of Good Hope. 

 The genus, with others represented in this research, is allied to Iris, Mor<m, and Tigridia. The 

 starch of only one species, H. collina Vent. {Morcea collina Thunb.), was available for study. 



Curve of Reaction-Intensitiea of Starch of 

 Moreea tristis. 



