GENUS CASTANEA. 



435 



The degree of polarization is fair to high. The proportion of grains in which polarization is 

 high is smaller than in C. americana. The variation in the same aspect of a given grain is the same 

 as in C. americana. On the whole, polarization is lower than in C. americana. 



With selenite the quadrants are not so well defined as in C. americana, but otherwi.se essentially 

 the same. The colors are pure in the larger number of grains, with considerable variation in the dif- 

 ferent grains and even in the same aspect of a given grain. 

 The yellow of one quadrant may be impure in parts, but 

 pure in the other three. The colors are not pure in as large 

 a proportion of the grains as in those of C. americana. 



Iodine Reactions. — With 0.25 per cent Lugol's solution 

 the grains color a rather deep violet, which becomes very 

 deep in 2 minutes; with 0.125 per cent solution the grains 

 color a very light reddish-violet, which deepens gradually 

 in 5 minutes. The color is a little deeper and of a more red- 

 dish tint than in C. americana. After heating in water until 

 all the grains are gelatinized, the solution becomes of a heli- 

 otrope color and the grains a reddish blue to a heliotrope 

 on the addition of iodine. If the grains are boiled for 2 

 minutes and then treated with iodine, the solution assumes 

 a deep purplish-blue and the grain-residues a light red- 

 violet. With an excess of iodine the capsules color an old- 

 rose to wine-red. There is rather more red color in the 

 solution, grain-residues, and capsules than in C. americana. 



Staining Reactions.- — With gentian violet and with 

 safranin there is no reaction at once, except in a few 



grains in which the deep central cleft is slightly colored. In 30 minutes the grains are lightly colored, 

 the tint being deeper at the cleft. The color is slightly deeper than in C. americana. 



Temperature Reaction. — The temperature of gelatinization is 59° to 60.5° C, mean 59.75°. 



Effects of Variotis Reagents. — With chloral hydrate-iodine reaction begins at once. A few grains 

 are gelatinized in 20 seconds, the majority in 30 seconds, and all in a minute except rare resistant 

 grains in which the reaction is usually complete in Ij^ minutes and rarely 3J^ minutes. The slit- 

 like structure which becomes irregular in outline during gelatinization is more frequently observed 

 than in C. americana. The reaction is qualitatively the same as in C. americana. 



Reaction with chromic acid begins at once and all the grains are dissolved in 15 seconds. The 

 reaction is qualitatively the same as in C americana. 



The reaction with pyrogallic acid begins at once. Many grains arc gelatinized in 5 seconds 

 and all in 10 seconds. The reaction is qualitatively the same as in C. americana. 



With ferric chloride swelling begins in a few grains in 20 seconds. A small number are gelatinized in 

 a minute, about half in 2 minutes, the majority in 3 minutes, and all in 4 minutes, except a few resistant 

 grains which may not be gelatinized for 10 to 27 minutes. The formation of a bubble at the hilum or 

 of a slit-like structure in the central part of the grain, which enlarges and then collapses, is more fre- 

 quently observed than in C. americana. The reaction is qualitatively the same as in C. americana. 



With Purdy's solution reaction begins immediately. A few grains are gelatinized in 10 seconds, 

 nearly all in 30 seconds, and all but a few resistant grains in a minute, the latter grains being com- 

 pletely gelatinized in 2 to 3 minutes. The reaction is qualitatively the same as in C. americana. 



Differentiation of Certain Starches of the Genus Castanea. 

 HisTOLoaicAi, Characteristics. HiSTOLoaicAL Chabactbbistics. — Continued. 



Curve of Reaction'Intensitiea of Starch of Castanea 

 pumila. 



Conspicuous Forms. 



C. americana: Usually simple, few aggregates and com- 

 pound grains, few pressure facets, surface irregular 

 owing chiefly to wart-like protuberances. Ovoid, 

 somewhat bean-shaped, ellipsoidal, club-shaped 

 with pointed end, piriform. 



C. salivaysiT. numbo: Essentially the same as in C. americana. 



C. saliva var. : Essentially the same as in C. americana, but 

 greater proportion of larger grains and irregular 

 grains. 



C. pumila: Essentially the same as in C. americana. 



Hilum — Form, Number, and Position. 



C. americana: Form usually not demonstrable, clear, 

 round spot; rarely an irregular cavity; single 

 longitudinal or a transverse or diagonal fissure. 

 Position usually eccentric about 0.4 to 0.3 of the 

 longitudinal axis. 



C. saliva var. numbo: Form same as in C. americana, but 

 fissures more often present and deeper. Posi- 

 tion usually eccentric about 0.4 to 0.2 of longi- 

 tudinal axis. 



