430 



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



one end of the grain; (3) to protuberances at different 

 points which vary from small nipple-like to finger-shaped 

 processes. The components of the aggregates are usually 

 compactly arranged, but three in linear arrangement 

 are rarely observed. The conspicuous forms are ellip- 

 soidal, ovoid, elongated ovoid, bean-shaped triangular 

 with rounded angles, pyriform, and lenticular. There 

 are also club-shaped, spindle-shaped, napiform, rod- 

 shaped with curved ends, imperfect quadrangular, 

 T-shaped, and indefinite forms. The grains are some- 

 what flattened. 



The hilum is usually very indistinct, but when demon- 

 strable it appears as either a small, round, or elliptical 

 spot which varies in position from centric to quite eccen- 

 tric. The eccentricity has a range usually of about 

 0.2 to 0.25, rarely as much as 0.15, of the longitudinal 

 axis. The hilum is, as a rule, not fissured. 



The lamella are usually very indistinct. When ob- 

 served near the hilum, they form moderately fine rings, 

 which according to the shape of the hilum are circular or 

 elliptical, but most of the lamella? closely follow the out- 

 line of the grain. The lamellae are rather fine with 

 occasionally one or two that are less fine and located at 

 varying distances from the hilum. On grains of medium 

 size about 8 to 10, and on the larger ones 16, rarely 20, 

 may be counted. 



The size varies from the smaller which are 4 by 3/*, 

 to the larger which are usually 38 by 20^, rarely 46 by 

 20ju, in length and breadth. The common size is about 

 26 by 14,*. 



Polariscopic Properties. 



The figure is centric to quite eccentric, and fairly 

 clear-cut. The lines vary from rather fine to quite broad, 

 and more frequently intersect obliquely. In the bean- 

 type they are so arranged as to form a mesial line with 

 bisected ends. The lines are often bent and bisected. 

 Double figures, either in the compound grains or aggre- 

 gates are rarely observed. 



The degree of polarization is high to very high (value 

 75). There is considerable variation in the different 

 grains, the range being from fair to quite high, with 

 the majority fairly high. A variation is also frequently 

 observed in the same aspect of a given grain. 



With selenite the quadrants are usually well defined 

 in the majority of grains, and usually unequal in size and 

 irregular in shape. The colors may be pure, but some- 

 times the blue, but more often the yellow, are not quite 

 pure. 



Iodine Reactions. 



With 0.25 Lugol's solution the grains color at once 

 a moderate to light violet (value 45) with a slight 

 reddish tint which deepens rapidly to a moderately 

 deep blue-violet. With 0.125 Lugol's solution the 

 grains color a light violet with reddish tint which 

 gradually becomes slightly deeper and much more blue. 

 After heating in water until the grains are gelatinized, 

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

 solution colors a deep indigo-blue, and the gelatinized 

 grains a light blue, a few of the larger ones with a red- 

 dish tint. If the preparation is boiled for 2 minutes and 

 then treated with an excess of iodine the grain-residues 

 color a light dull-blue with a reddish tint, and the cap- 

 sules color a light to a deep old-rose. 



Aniline Reactions. 

 The grains begin to stain immediately, and in half an 

 hour they are colored moderate to deep (value 60). 



With safranin the grains begin to stain immediately, 

 and in half an hour they are colored moderate to deep 

 (value 60). 



Temperature Reactions. 

 The majority of the grains are gelatinized at 79° 

 to 81° C, and all at 82° to 84° C, mean 83° C. 



Effects of Various Reagents. 



The reaction with chloral hydrate begins in a few 

 grains in 1 minute. Complete gelatinization occurs in 

 about 6 per cent of the entire number of grains and 7 

 per cent of the total starch in 5 minutes; in about 15 

 per cent of the grains and 20 per cent of the total starch 

 in 15 minutes ; in about 47 per cent of the grains and 60 

 per cent of the total starch in 30 minutes; in about 55 

 per cent of the grains and 67 per cent of the total starch 

 in 45 minutes; in. about 60 per cent of the grains and 74 

 per cent of the total starch in 60 minutes. (Chart D 85.) 



A very small bubble may appear at the hilum which 

 usually expands very little and is very persistent. The 

 lamella? do not become more distinct. The entire grain 

 becomes more refractive and a very narrow border of 

 greater refractivity forms around the grain, and this 

 border gradually broadens and becomes a little more 

 sharply differentiated. Gelatinization begins at the dis- 

 tal end of grains that have a clearly defined, eccentric 

 hilum, and proceeds toward the proximal end where is 

 located the most resistant starch. In more irregular 

 grains the process may start at any prominent corner; 

 and in elongated grains with nearly centric hilum gela- 

 tinization may start simultaneously at both ends and 

 progress towards the hilum. In the last-named grains, 

 as the reaction approaches the hilar region from either 

 end, a cleft furrows through the hilum, accompanied with 

 the expulsion of the bubble thereat, the most resistant 

 starch being a narrow band at either side of the hilar 

 region including the bilateral border. During the process 

 the capsule is distended and much distorted. The re- 

 sistant starch is often broken into refractive masses and 

 sometimes into refractive granules previous to gela- 

 tinization. When a narow band of starch at the proxi- 

 mal end and sides nearby is the most resistant, it may 

 be penetrated by numerous short, deep fissures previous 

 to breaking into linearly arranged refractive granules. 



• The gelatinized grains are swollen and considerably 

 distorted. Many grains are little affected beyond the 

 initial stages, while others have varying amounts of un- 

 gelatinized starch remaining. 



The reaction with chromic acid begins in very rare 

 grains in 1 minute. Complete gelatinization occurs in 

 very rare grains (less than 0.5 per cent of the entire 

 number) and less than 0.5 per cent of the total starch 

 in 5 minutes; in about 1 per cent of the grains and 5 

 per cent of the total starch in 15 minutes ; in about 3 per 

 cent of the grains and 23 per cent of the total starch in 

 30 minutes ; in about 15 per cent of the grains and 92 per 

 cent of the total starch in 45 minutes ; in about 30 per 

 cent of the grains and 97 per cent of the total starch in 

 60 minutes. (Chart D 86.) 



The reaction with pyrogallic acid begins in a few 

 grains in 1 minute. Gelatinization occurs in about 2 



