GENUS QUERCUS. 



425 



Qiart No. 66. 



Gv S T CI CA PA FC P S CI PA CA 

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5 1 



The elongated central cleft is marked in this species, as well as the eccentric hilum \vith one 

 lonKitiicliiial fissure or other peculiarities at this region, already described for Q. alba. The clefts 

 are, liowever, not so deep nor found in so large a proportion of grains as in Q. alba. The hilum when 

 demonstrable is about one-third to two-fifths eccentric; rarely it is centric. 



The lamellw are less often demonstrable than in the grains of Q. alba, but occasionally grains 

 are seen in which 8 can be counted. They are of similar structure to those of Q. alba. 



The grains vary in size from the small, which are 4 by 3^1, to the larger, which are 24 by 14fi. 

 The common size is 16 by 10//. 



Polariscopic Propeiiies. The figure is usually eccentric and fairly clear-cut. There are several 

 grains which show the bean type of figure found in Q. alba, and a few in which the figure is centric 

 or nearly centric. The lines generally intersect obliquely, 

 and are not so frequently bent or bisected as in Q. alba. 



The degree of polarization is fair to quite high. The 

 percentage of grains in which the polarization is high is 

 not so great as in Q. alba. Polarization, on the whole, 

 is somewhat lower than in Q. alba. 



With selenite the quadrants are usually well defined, 

 slightly irregular in shape, and unequal in size. The colors 

 are the same as those noted for Q. alba, but the percent- 

 age of grains in which the colors are bright and pure is 

 not so high as in Q. alba. The colors are generally pure. 



Iodine Reactions. With 0.25 per cent Lugol's solu- 

 tion the grains color a rather hght violet, which deepens 

 rather slowly; with 0.125 per cent solution the grains 

 slowly take on a very light violet tint, which deepens 

 slightly. The color of the grains when treated with these 

 solutions is lighter and more reddish than in Q. alba. After 

 heating in water until all the grains are completely gelat- 

 inized the solution colors light indigo-blue and the gelat- 

 inized grains a deep bluish-purple on the addition of 

 iodine. If the preparation is then boiled for 2 minutes and afterwards treated with iodine, the solu- 

 tion colors a deep reddish-purple and the grain-residues a light bluish-violet. With an excess of 

 iodine the giain-residues are colored a deep reddish-purple and the capsules a reddish-violet to deep 

 old-rose. When treated with iodine the gelatinized grains and grain-residues have slightly more of 

 a reddish tint than those of Q. alba. 



Staining Reactions. With gentian violet the grains do not stain immediately, but in 30 minutes 

 have colored slightly. There is some variation in the depth of color of the different grains. The 

 color is not quite so deep in the majority of the grains as in those of Q. alba. 



With safranin the grains do not stain immediately, but in 30 minutes they have colored slightly. 

 The larger grains are of about the same tint as those of Q. alba, but the smaller grains, which form 

 the majority, do not stain quite so much as the grains of Q. alba. 



Temperature Reaction. The temperature of gelatinization is 64 to 65.8 C, mean 64.75. 



Effects of Various Reagents. -With chloral hydrate-iodine the reaction begins in a few grains 

 in 30 seconds. A few are gelatinized in a minute, about four-fifths in 3 minutes, practically all in 5 

 minutes, and all in within 23 minutes. The process is qualitatively the same as in Q. alba. 



The reaction with chromic acid begins at once and most grains are dissolved in 35 seconds, 

 while a very few resist the effects of the reagent for 60 seconds. The reaction is qualitatively the 

 same as in Q. alba. 



With pyrogallic acid the reaction begins at once and is complete in all grains in 45 seconds. 

 The process is qualitatively the same as in Q. aJba. 



Reaction with ferric chloride begins in a few grains in a minute. A few are gelatinized in 5 

 minutes, about one-fifth in 10 minutes, about four-fifths in 15 minutes, all but a few scattered grains 

 (one in several hundred) in 30 minutes, and all in an hour. The reaction is quahtatively the same 

 as in Q. alba. 



Reaction with Purdy's solution begins in a few grains inamediately and all are in various stages 

 of gelatinization in 5 minutes. There is a gradual change in 10 minutes. Gelatinization is complete 



Curve of Reaction-Intensities o( Starch of Quercus 

 prinus. 



