702 



DATA OF PROPERTIES OP STARCHES OF PARENT- AND HYBRID-STOCKS. 



The reaction with cobalt nitrate begins in a few- 

 grains in 30 seconds. Complete gelatinization occurs in 

 less than 0.5 per cent of the entire number of grains and 



3 per cent of the total starch in 5 minutes ; in less than 

 0.5 per cent of the grains and 10 per cent of the total 

 starch in 15 minutes ; in about 4 per cent of the grains and 

 27 per cent of the total starch in 30 minutes; in about 14 

 per cent of the grains and 44 per cent of the total starch 

 in 45 minutes; little if any advance in GO minutes. 

 (Chart D 522.) 



The reaction with copper nitrate begins immediately. 

 Complete gelatinization occurs in about 50 per cent of 

 the entire number of grains and 80 per cent of the total 

 starch in 2 minutes; in about 73 per cent of the grains 

 and 95 per cent of the total starch in 5 minutes; in 

 about 90 per cent of the grains and in more than 99 

 per cent of the total starch in 15 minutes. (Chart 

 D523.) 



The reaction with cupric chloride begins in a few 

 grains in 30 seconds. Complete gelatinization occurs in 

 about 20 per cent of the entire number of grains and 75 

 per cent of the total starch in 3 minutes; in about 44 

 per cent of the grains and 90 per cent of the total starch 

 in 5 minutes; in about 70 per cent of the grains and 98 

 per cent of the total starch in 15 minutes. (Chart 

 D524.) 



A small area at the distal end in a number of grains is 

 very resistant and a small percentage of grains (about 



10 per cent) may still be ungelatinized at this point in 

 GO minutes. This part of the grain is much more re- 

 sistant than in B. single crimson scarlet, but the grains 

 arc much less resistant than in B. socotrana. 



The reaction with barium chloride begins in a few 

 grains in 1 minute. Complete gelatinization occurs in 

 less than 0.5 per cent of the entire number of grains and 

 1 per cent of the total starch in 5 minutes; in about 1 

 per cent of the grains and 8 per cent of the total starch 

 in 15 minutes; in about 2 per cent of the grains and 



11 per cent of the total starch in 30 minutes; in about 



4 per cent of the grains and 16 per cent of the total starch 

 in 45 minutes ; little if any further advance in 60 minutes. 

 (Chart D 525.) 



The reaction with mercuric chloride begins in a few 

 grains in 1 minute. Complete gelatinization occurs in 

 less than 0.5 per cent of the entire number of grains and 

 10 per cent of the total starch in 5 minutes; in about 

 10 per cent of the grains and 30 per cent of the total 

 starch in 15 minutes; in about 33 per cent of the grains 

 and 63 per cent of the total starch in 30 minutes; in 

 about 39 per cent of the grains and 71 per cent of the 

 total starch in 45 minutes; in about 44 per cent of the 

 grains and 80 per cent of the total starch in 60 minutes. 

 (Chart D 526.) 



37. Stakches of Begonia double light rose, B. 

 socotrana, and b. ensign. 



Begonia double light rose (Seed Parent). 



(Plate 21, fig. 124; Charts D 527 to D 532.) 

 Histologic Properties. 

 In form the grains are always simple and usually 

 isolated. An occasional doublet or quadruplet is seen. 

 The grains are usually regular in form, and any irregu- 

 larities that occur are slight and due to the following 



causes: (1) A slight deviation of the longitudinal axis 

 of the grain and a consequent bending of the grain ; 

 (2) a greater development of one side, or of the proxi- 

 mal end or of one portion of the distal end than the 

 rest; (3) an occasional depression in the margin, usually 

 at the distal end; (4) rarely, 1 or 2 large protuberances 

 from the side ; (5) rarely, secondary lamella? whose axis is 

 at a right or an acute angle to the axis of the primary 

 set. The conspicuous forms are elliptical with squared 

 or rounded distal end, ovoid, and nearly round. The 

 additional forms are round, pyriform, and club-shaped. 

 The grains are not flattened. 



The hilum is a moderately distinct, round spot which 

 is usually not fissured. The fissures, when present, have 

 the following forms: (1) A single short, straight line; 

 (2) a small, irrregular Y- or T-shape; (3) an irregu- 

 larly stellate arrangement of a number of short fissures. 

 The hilum is rarely centric, and in the great majority 

 of the grains is eccentric from 0.44 to 0.29, commonly 

 0.31, of the longitudinal axis. 



The lamella are fine and moderately distinct. Near 

 the hilum they are continuous, round rings, and near 

 the margin they become discontinuous and have the form 

 of the outline of the grain. In some grains they are 

 more distinct and less fine near the hilum, and in others 

 near the distal end. In most of the grains there is a 

 coarse, more or less refractive lamella situated one- 

 fourth, one-half, or five-sixths of the distance from the 

 hilum to the margin, and in some grains there is a band 

 of 3 or 4 such coarse lamellae about one-half to two-thirds 

 of the way from the hilum to the margin. The number 

 of lamellae counted on the larger grains varies from 15 

 to 33, usually 24. 



In size the grains vary from the smaller which are 

 6 by 6/t, to the larger which are 34 by 27/*, in length 

 and breadth. The sizes are 24 by 20/* and 18 by 18/t 

 in length and breadth. 



Polariscopic Properties. 



The figure is distinct and well defined. The lines 

 are rather thick and cross at a right angle or at an acute 

 angle which does not vary greatly in different grains. 

 They are often somewhat bent and occasionally bisected. 



The degree of polarization varies from moderately 

 high to high (value 70). There is no variation in a 

 given aspect of an individual grain. 



With selenite the quadrants are clear-cut, and usually 

 unequal in size, and often somewhat irregular in shape. 

 The colors are usually pure, with the exception of a 

 moderate number of grains which have a greenish tinge. 



Iodine Reactions. 

 With 0.25 per cent Lugol's solution the grains all 

 color a moderate blue tinged with violet (value 45) . The 

 color deepens rapidly until it is very deep and has 

 assumed more of a bluish tint. With 0.125 per cent 

 Lugol's solution the grains all color a light blue-violet, 

 and the color deepens rapidly until it is deep. After 

 heating in water until the grains are all gelatinized 

 and then treating with a 2 per cent Lugol's solution, the 

 gelatinized grains usually color a moderately light, a few 

 a light, and a few a deep indigo ; and the solution a deep 

 indigo. If the preparation is boiled for 2 minutes and 

 then treated with an excess of a 2 per cent Lugol's solu- 



