668 



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



the total starch in 5 minutes; in about 9 per cent of the 

 grains and 16 per cent of the total starch in 15 minutes; 

 in about 10 per cent of the grains and 32 per cent of the 

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

 grains and 43 per cent of the total starch in 45 minutes ; 

 in about the same percentage of the grains and 47 per 

 cent of the total starch in 60 minutes. (Chart D461.) 

 The reaction with mercuric chloride begins imme- 

 diately. Complete gelatinization occurs in about 4 per 

 cent of the entire number of grains and 23 per cent of the 

 total starch in 5 minutes; in about 45 per cent of the 

 grains and 77 per cent of the total starch in 15 minutes ; 

 in about 63 per cent of the grains and 87 per cent of the 

 total starch in 30 minutes; in about 71 per cent of the 

 grains and 95 per cent of the total starch in 45 minutes; 

 in about 75 per cent of the grains and 96 per cent of the 

 total starch in 60 minutes. (Chart D 462.) 



IRIS SINDJARENSIS (POLLEN PARENT). 



(Plate 19, fig. 113; Charts D 442 to D 462.) 



HISTOLOGIC PBOPERTIES. 



In form a small majority of the grains are simple 

 and usually isolated. Only a few aggregates in the 

 form of small doublets of equal-sized grains are noted. 

 There are many more compound grains than in /. persica 

 var. purpurea, which usually consist of 2 to 3, but some- 

 times of 8 or 9, components, and all belonging to one or 

 another of three types. The first type, which is the most 

 common, consists of 2 or more components each repre- 

 sented by a hilum and 1 lamella, arranged linearly or 

 irregularly in a homogeneous-looking space and sur- 

 rounded by 4 to 6 or 7 common secondary lamellae. The 

 second type consists of 2 to 3 components linearly 

 arranged, each consisting of a hilum and 2 or 3 lamellas 

 and all surrounded by 2 to 4 common secondary lamellae, 

 a type which is not nearly so common as in I. persica 

 var. purpurea. The third type, which is more numerous 

 than in I. persica var. purpurea, consists of a large, sim- 

 ple or compound grain, to the side or end of which one 

 or more small, simple or compound grains have become 

 attached, and the whole surrounded by 1 or 2 common 

 lamellae. The grains are usually moderately regular in 

 form, much more regular than in /. persica var. purpurea, 

 and any irregularities which occur are due to the follow- 

 ing causes in the order of frequency of occurrence: (1) 

 To small, pointed or rounded protuberances usually 

 from the sides, but sometimes from the distal or proximal 

 ends; (2) a secondary set of lamellae whose longitudinal 

 axis is usually at a right angle with that of the primary 

 set ; (3) to very few and very shallow depressions and ele- 

 vations of the surface of a grain producing an undulating 

 or wavy outline of the margin; (4) rarely, a small, 

 shallow notch on the middle of the distal margin. The 

 conspicuous forms of the simple grains are ovoid and 

 elliptical, both often with a flattened distal end ; and of 

 the compound grains, nearly round, ovoid, and elliptical 

 with both ends rounded. The additional forms of the 

 simple grains are lenticular, round and nearly round, 

 dome-shaped and irregularly quadrilateral with rounded 

 angles ; and of the compound grains, irregularly quadri- 

 lateral with rounded angles, dome-shaped, and triangu- 

 lar. The grains are not flattened. 



The hilum, when not fissured, is more distinct than in 

 I. persica var. purpurea, and is a round or lenticular, 



refractive spot. It is, however, usually fissured, but not 

 so often, nor so irregularly, nor so extensively as in 

 I. persica var. purpurea. The fissures have the following 

 forms: (1) 2 lines somewhat branched, forming an angle 

 like a pair of dividers, crossing which lines near the 

 angle there may be a single, straight, horizontal line; 

 (2) Y-shaped; (3) an irregularly stellate arrangement 

 of many fissures; (4) rarely, a single, straight, trans- 

 verse or oblique line. In the compound grains the hila are 

 sometimes separated from one another by fissures which 

 do not extend to the margin, but in no case was a single 

 fissure noted, as in /. persica var. purpurea, which passes 

 through all the hila. The hilum is sometimes centric but 

 is commonly eccentric from 0.44 to 0.27, usually 0.31, 

 of the longitudinal axis. The hilum is usually 0.04 more 

 eccentric than that of 7. persica var. purpurea. 



The lamella are as distinct as in /. persica var. pur- 

 purea, but are not so coarse and are more regular in out- 

 line. Near the hilum they are round, and rarely ellipti- 

 cal, in outline, and near the margin they follow the form 

 of the contour of the grain. The number counted on the 

 larger grains varies from 6 to 15, usually 12, larger than 

 in /. persica var. purpurea. 



In size the grains vary from the smaller which are 

 2 by 2ju, to the larger elongated forms which are 42 by 

 24/t, and the larger broader forms which are 42 by 34/t, 

 in length and breadth. The common sizes are 26 by 18ju 

 and 26 by 24/i. The common sizes of /. sandjarensis are 

 6//, shorter and S/n narrower and 6/^ shorter and 2/j. nar- 

 rower, and, on the whole, smaller than that of 7. persica 

 var. purpurea. 



POLABISCOPIC PROPERTIES. 



The figure is as distinct as in 7. persica var. purpurea 

 and much better defined than in that starch. The lines 

 cross more often at a right angle and where they do not 

 there is less variation in the size of the acute angles than 

 in /. persica var. purpurea. They are not so often bent 

 nor so often divided into 2, 3, or 4 divisions as in that 

 starch. 



The degree of polarization varies from moderately 

 high to very high (value 75), 5 units higher than in 

 7. persica var. purpurea. There is also less variation 

 in the same aspect of a given grain as in that starch. 



With selenite the quadrants are much more clear-cut. 

 They are not so unequal in size nor so irregular in shape 

 as in I. persica var. purpurea. The colors are usually 

 pure, but there are more grains which have a greenish 

 tinge than in that starch. 



IODINE REACTIONS. 



With 0.25 per cent Lugol's solution the grains all 

 color a moderate blue-violet (value 50), 5 units less than 

 in 7. persica var. purpurea. The color deepens rapidly 

 until it is very deep and at the same time has assumed 

 more of a bluish tint. With 0.125 per cent Lugol's solu- 

 tion the grains all color a light blue-violet, less than in 

 7. persica var. purpurea, and the color deepens with 

 moderate rapidity until it is very deep and at the same 

 time has assumed more of a bluish tint. After heating 

 in water until all the grains are completely gelatinized, 

 then treating with 2 per cent Lugol's solution, the gela- 

 tinized grains are colored a light or a light to moderate 

 indigo, less than in 7. persica var. purpurea; and the 

 solution a very deep indigo, more than in 7. persica var. 



