656 



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



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

 0.5 per cent of the grains and 5 per cent of the total 

 starch in 15 minutes; in about 1 per cent of the grains 

 and 6 per cent of the total starch in 30 minutes; in 

 about 2 per cent of the grains and 8 per cent of the total 

 starch in 45 minutes ; in about 3 per cent of the grains 

 and 12 per cent of the total starch in 60 minutes. (Chart 

 D419.) 



The reaction with mercuric chloride begins in a few 

 grains in 1 minute. Complete gelatinization occurs in 

 about 0.5 per cent of the entire number of grains and 

 6 per cent of the total starch in 5 minutes; in about 2 

 per cent of the grains and 11 per cent of the total starch 

 in 15 minutes; in about 4 per cent of the grains and 17 

 per cent of the total starch in 30 minutes; in about 5 

 per cent of the grains and 21 per cent of the total starch 

 in 45 minutes; in about the same percentage of the 

 grains and 22 per cent of the total starch in 60 minutes. 

 (Chart D 420.) 



32. Starches of Iris cengialti., I. pallida queen 



OF MAY, AND I. MRS. ALLAN GREY. 



Starch of Iris cengialti (seed parent) is described 

 in pages 647 to 652. 



I. PALLIDA QUEEN OF MAY (POLLEN PARENT ). 



(Plate 19, fig. 110; Charts D 421 to D 441.) 



Histologic Properties. 



In form the grains are usually simple and isolated, 

 but both compound grains and aggregates occur in mod- 

 erate numbers. The compound grains belong to two 

 types: (1) 2 small grains are adherent and sur- 

 rounded by a number of common secondary lamellae 

 and located either at the proximal end or in the middle 

 of a large grain (the exact number of lamella? often 

 can not be determined) ; (2) 2 or 3 grains are adherent 

 to a larger grain and all surrounded by one common layer 

 of starch, forming a very irregular compound grain. 

 The aggregates are usually doublets of equal size, but 

 sometimes consist of 3 or 4 grains adherent to one an- 

 other in irregular manner. The grains are often irregu- 

 lar in form and the irregularities are due to the follow- 

 ing causes: (1) a secondary set of lamella? usually 

 situated near the proximal end or middle of the grain 

 whose longitudinal axis is at an angle, usually a right 

 angle, with that of the primary set; (2) a deviation of 

 the axis with a consequent bending of the grain in the 

 middle or near the distal end; (3) shallow depressions 

 and elevations of the surface and margin, often consist- 

 ing of 1, 2, or 3 regular enlargements and constrictions 

 of the grain throughout its length; (4) rarely a small 

 protuberance, usually at the distal end; (5) rarely a deep 

 notch in the distal margin. The conspicuous forms are 

 elongated elliptic and elongated ovoid, both with flat- 

 tened distal ends, and pyriform. The additional forms 

 are club-, rod-, finger-, boot-, and hammer-shaped, and 

 nearly round. The grains are not flattened. 



The hilum is usually a moderately distinct, round 

 spot. It is seldom fissured and the fissures are not deep 

 nor extensive. They have the following forms: (1) 

 A short, straight, transverse line; (2) a flying-bird 

 figure. The hilum is eccentric from 0.4 to 0.25, com- 

 monly 0.29, of the longitudinal axis. 



The lamella? are usually moderately distinct and 

 rather coarse. Near the hilum they are generally not so 

 distinct nor so coarse as in the rest of the grain. They 

 are continuous except near the margin and usually have 

 the form of the outline of the grain, except that they 

 have a flattened portion in the longitudinal axis of the 

 grain. There are often 2 or 3 especially coarse and dis- 

 tinct lamellae situated respectively one-half, two-thirds, 

 and three-fourths of the distance from the hilum to the 

 distal margin. The number counted on some of the 

 larger grains varies from 8 to 20, usually 15. 



In size the grains vary from the smaller which are 

 4 by 4/*, to the larger which are 24 by 10fi, in length 

 and breadth. The common sizes are 14 by 6^ and 14 

 by 9/i. 



Comparison of the histologic properties between 7. 

 cengialti and I. pallida queen of may shows : 



There are fewer compound grains and aggregates. 

 The compound grains consist of an irregular mass of 

 3 to 5 or 6 component grains surrounded by 1 common 

 layer of starch. The aggregates are doublets of equal- 

 sized grains. The grains are not so irregular as in 

 I. pallida queen of may, and the irregularities are due 

 to the same causes, but secondary sets of lamellae and 

 deviation of the longitudinal axis are not nearly so com- 

 mon as in that starch. The conspicuous forms are not 

 very different, but are more rounded and not so slender 

 as in I. pallida queen of may. 



The hilum when not fissured is more distinct. It is 

 usually fissured, much more often and also much more 

 deeply and more extensively than in I. pallida queen of 

 may. The fissures have the following forms of which 

 the first two are the same as in I. pallida queen of may: 

 (1) A single, straight line; (2) a flying-bird figure; 

 (3) a V-shaped figure sometimes crossed by a straight, 

 transverse fissure; (4) an irregularly stellate arrange- 

 ment of fissures. The hilum is usually more eccentric 0.04 

 of the longitudinal axis than in I. pallida queen of may. 



The lamellce are generally not so distinct and are 

 coarser than in I. pallida queen of may. Usually only 

 1 very coarse lamella is seen at half the distance from 

 the hilum to the margin. There is also often a notch 

 in the outline of the lamellae, as a rule, corresponding to a 

 notch in the distal margin, which is not seen in I. pallida 

 queen of may. 



In size the grains are larger than those of I. pallida 

 queen of may. The large grains are 6^ longer and 

 6/t broader than those of I. pallida queen of may, and the 

 common-sized grains are 8/j. longer and 8 to 6p broader 

 than those of I. pallida queen of may. 



Polariscopio Properties. 



The figure is usually moderately distinct and well 

 defined. The lines usually cross at a very acute angle 

 which does not vary greatly in different grains. They are 

 very often much bent and often also bisected. The 

 figure moderately often has the form of a compound 

 hyperbola or of a long line bisected at both ends. 



The degree of polarization varies from low to high 

 (value 50). In most of the grains it is moderate and 

 in a few it is low, and in the rest it is moderately high 

 and high. There is some variation in a given aspect 

 of the individual grains. 



