426 



STARCHES OF CUPULIFER^. 



in about nine-tenths in 15 minutes and in all in 30 minutes. The reaction is qualitatively the same 

 as in Q. alba, but the process is not so complete. Not so many of the lamellfe become gelatinized 

 as in the grains of Q. miiehlenhcrgi, but the resemblance to this grain is closer than to Q. alba. 



STARCH OF QUERCUS RUBRA. (Plate 12, fig. 67. Chart 67.) 



Histological Characteristics. In form nearly all of the grains are simple; the compound grains 

 are usually of two components. The simple grains are isolated, except a few which occur in small 

 aggregates and many in clumps. The conspicuous forms are the same as those of Q. alba, except 

 that the ellipsoidal, ovoid, pyriform, and nearly round are relatively much more ninnerous. Grains 

 with wart-like excrescences are noted, but, as a rule, the surfaces of the grains are much less irreg- 

 ular than those of Q. alba. 



The hilum is usually one-third to two-fifths eccentric. From the hilum there proceeds in some 

 grains a longitudinal cleft which becomes divided near the distal end into two or three divisions, 

 resemljling a 2- or 3-pronged fork. In other grains two fissures may start from the hilum or from 

 a small transverse fissure just below the hilum. In the 

 bean-shaped and also in some of the ellipsoidal grains a 

 cleft like that noted under Q. alba is observed. In the 

 round grains the hilum appears as a small centric, round 

 cavity. In the pyriform grains a transverse or diagonal 

 cleft is sometimes present at the hilum, and if the longi- 

 tudinal cleft is single the two form a cross. 



The lajnelhe are not demonstrable. 



The size varies from the smaller forms, which are 4 

 by 3n, to the larger, which are 18 by 10m 'u length and 

 breadth. The common size is 12 by 7m in length and 

 breadth. 



Polariscoyic Properties. The figure is usually ec- 

 centric and the bean type so often fountl in Q. alba is 

 sometimes observed. The lines of the figure generally 

 intersect obliquely and are more often straight than in 

 Q. alba. 



The degree of polarization is low to fairly high, fre- 

 quently varying in the same aspect of a given grain; some- 

 times quite low at both ends and very often in one end 

 it is very low or absent. This condition is prol)al)ly causeil by the forked cleft at the distal end. 



With sclcnilc one of the quadrants is frequently not well defined in the larger grains, but the 

 appearance noted in Q. alba is sometimes observed. They arc usually irregular in shape and unequal 

 in size. The colors are fairly bright, but less so than in Q. alba. The colors are gcneralh' pure. 



Iodine Reactions.- With 0.25 per cent Lugol's solution most grains color a very light red-violet, 

 and most of them deepen in tint very little; with 0.125 per cent solution a few of the grains color 

 either a very light red-violet or light old-rose, and the color deepens slightly and rather slowly. 



When the grains are heated in water until all are gelatinized, the solution does not color at all on 

 the addition of iodine, but the grains change to a deep reddish-purple. If the preparation is boiled 

 for 2 minutes and then treated ^vith iodine, the solution colors a deep bluish-violet, but most of the 

 grain-re.sidues do not color at all, while some become a light reddish-violet tint. With an excess 

 of iodine all the grain-residues color a deep red-violet to purple, while the capsules assume an old- 

 rose to a wine-color. The colors throughout the iodine reactions have more of a reddish tint than 

 in Q. alba. 



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

 minutes the color has slightlj' deepened. The stain acts more upon the grain at the cleft than at 

 the margin. There is considerable variation in the tint of the dilTerent grains. The depth of color- 

 ation is about the same as in Q. alba. 



With safranin the gi-ains stain very faintly at once and in 30 minutes they deepen slightly in 

 color, particularly at the central cleft. There is consideral:>le variation in the depth of tint in the 

 different grains. The color is very light, but slightly deeper than in Q. alba. 



Temperature Reaction. The temperature of gelatinization is 02.5 to (33.5 C, mean 63. 



Curve of Reaction-Intensities of Starch of Quercus rubra. 



