428 STARCHES OF CUPULIPERiE. 



The degree of polarization is fair to fairly high. It frequently varies in the same aspect of a 

 given grain, one quadrant being much lower than the others. This difference may be caused by 

 fissuration at the distal end. Polarization is slightly higher than in the grains of Q. rubra, but not 

 so high as in Q. alba. 



With selenite one of the quadrants is frequently not well defined, but the general appearances noted 

 in Q. alba are present. They are usually irregular in shape and unequal in size. The colors are slightly 

 brighter than in Q. rubra, but not so bright or so pure as in Q. alba. The colors are generally pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution most grains color a light reddish-violet. 

 In 5 minutes the color becomes fairly deep and in 10 minutes it is a very deep purple; with 0.125 per 

 cent solution many grains color a very light red-violet, which deepens in 5 minutes and in 10 minutes 

 becomes quite deep. Some of the grains in each preparation do not color. After heating in water 

 until all are gelatinized, the solution does not color at all, but the grains assume a very deep blue- 

 violet on the addition of iodine. When the solution is boiled for 2 minutes and then treated with 

 iodine, the solution takes on a deep-violet color, but the grain-residues remain colorless. With an ex- 

 cess of iodine the solution changes to a deep bluish-purple, while the capsules color a deep rose-violet. 



Staining Reactions. — With gentian violet the grains stain a very light violet at once and in 30 

 minutes have become fairly deeply colored. Some grains stain much more deeply than others. 

 The coloration is about the same as in Q. alba. 



With safranin the grains stain a light pink immediately and in 30 minutes they deepen slightly. 

 Some of the grains stain much more deeply than others. The stain is deeper than in Q. alba. The 

 color is slightly deeper than in Q. rubra. 



Temperature Reaction. — The temperature of gelatinization is 64° to 64.5° C, mean 64.25°. 



Effects of Various Reagents. — ^With chloral hydrate-iodine the reaction begins at once. A few 

 are gelatinized in 40 seconds, practically all in 2 minutes, and all in 6 minutes. The color of the 

 grains when observed after 3 hours is blue with a reddish tint. This more resembles the color of 

 Q. rubra than of Q. alba. The reaction is qualitatively the same as in Q. alba. 



Reaction with chromic add begins at once and the grains are dissolved in 20 seconds. The 

 reaction is qualitatively the same as in Q. alba. 



The reaction with pyrogallic acid begins at once and is complete in all the grains in 28 seconds. 

 The reaction is qualitatively the same as in Q. alba. 



With ferric chloride reaction begins in a few grains in 45 seconds. Practically all are in various 

 stages of gelatinization in 5 minutes, about two-thirds are gelatinized in 10 minutes, and all in 15 

 minutes, excepting a very few resistant grains (one in several hundi-eds) in which gelatinization is 

 usually complete in 30 minutes. The gelatinized grain is much swollen, but often retains the shape 

 of the untreated grain. It is more regular in outline than those of Q. alba. The reaction is quali- 

 tatively the same as that of Q. alba, but during the process particles are not broken off from the 

 larger resistant mass of starch with so much force as in Q. alba. 



The reaction with Purdy's solution begins at once in a few grains and practically all are in vari- 

 ous stages of gelatinization in 5 minutes. Gradual changes occur, but even in an hour quite a broad 

 border of resistant starch remains around the central gelatinized portion. The reaction is quali- 

 tatively the same as in Q. alba, but gelatinization is not so complete as in this species. It proceeds 

 somewhat further than in Q. rubra. 



Differentiation of Certain Starches of the Genus Quercus. 



HlBTOLOGICAL ChABACTERISTICS. 



Conspicuotis Forms. 



Q. alba: Simple, few compound, isolated except a few 

 small aggregates and clumps. ElUpsoidal, some- 

 what bean-shaped, ovoid, lenticular, and irregular 

 of indefinite form. 



Q. muehlenbergi: Same as in Q. alba, but fewer aggregates 

 and irregular grains. A larger percentage of ovoid, 

 ellipsoidal and pyriform. 



Q. prinus: Same as in Q. alba, but fewer aggregates and 

 irregular grains. A larger percentage of ellipsoidal, 

 ovoid, and lenticular grains. 



Histological Chabactekistics. — Continued. 



Conspicuous Forms. — Continued. 



Q. texana: Same as in Q. alba, but fewer aggregates and 

 the grains are not quite so irregular in outline. 

 A Im^er percentage of ellipsoidal, ovoid, and 

 pyriform. 



Hilum — Form, Number, and Posilum. 



Q. alba: Hilum usually deeply and extensively fissured; 



when not fissured, a clear round or lenticular spot. 



Position usually eccentric 0.4 to 0.3. 

 Q. muehlenbergi: Same as in Q. alba, but the hilum more 



Q. rubra: Same as in Q. ai6a, except fewer aggregates and j often demonstrable and the fissure when pres- 



irregular grains, but more clumps; a larger percent- ent not so deep. Po.sition usually eccentric 0.3 



agcofellipsoidaJ,ovoid,pyrifonu,andnearlyround. I to 0.4. 



