774 



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



This preparation is more easily followed than in C. 

 rosea since there are fewer oxalate needles, hence much 

 less disturbance from the evolution of bubbles, and there 

 is very little solution of entire grains. The grains of this 

 species are apparently of even density throughout and 

 usually of regular outline, very much more than in 

 G. rosea; when the larger grains are observed under the 

 polariscope, however, the mesial portion has a lower 

 degree of polarization than the margin. 



Gelatinization begins and proceeds as noted for the 

 grains of even density and regular form in C. rosea. 

 The narrow border of more resistant starch frequently 

 consists of 2 or 3 clearly defined lamella? which are 

 striated and may later break into linearly arranged 

 refractive granules ; this border is generally broader than 

 in C. rosea. The border may become dissolved at the 

 distal end, but the entire grains are not usually dis- 

 solved ; this border is far more resistant than in C. rosea. 

 The gelatinized grains are somewhat swollen but not 

 usually distorted as in C. rosea; a large proportion do not 

 become completely gelatinized since the narrow border 

 above noted resists the reagent. 



The reaction with pyrogallic acid begins in 1 minute. 

 Complete gelatinization occurs in but rare grains, less 

 than 0.5 per cent of the entire number, and 10 per cent 

 of the total starch in 5 minutes; complete gelatinization 

 still occurs in less than 0.5 per cent of the entire number 

 of grains and 20 per cent of the total starch in 15 min- 

 utes; complete gelatinization occurs in about 1 per cent 

 of the entire number of grains and 60 per cent of the 

 total starch in 30 minutes; in about 8 per cent of the 

 entire number of grains and 84 per cent of the total 

 starch in 45 minutes; in about 15 per cent of the grains 

 and 89 per cent of the total starch in 60 minutes. (Chart 

 D 621.) 



The reaction with nitric acid begins immediately 

 in a few grains. Complete gelatinization occurs in about 

 5 per cent of the entire number of grains and 61 per cent 

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

 the grains and 64 per cent of the total starch in 15 min- 

 utes; in about 13 per cent of the grains and 71 per cent 

 of the total starch in 30 minutes; in about 15 per cent 

 of the grains and 73 per cent of the total starch in 45 

 minutes; in about 18 per cent of the grains and 78 

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

 D 622.) 



The reaction begins immediately; a few grains are 

 gelatinized in 15 minutes; the majority in 1 minute; 

 nearly all in 1% minutes, all but a few resistant grains 

 in 2 minutes and all in 3 minutes. A small bubble 

 appears at the hilum and is soon expelled ; fissures pro- 

 ceed from the swollen hilum to the distal margin, and 

 when these fissures are obliquely directed towards the 

 distal corners, the lamella? between them become sharply 

 defined and striated. Gelatinization proceeds more 

 rapidly now at the distal margin and then the refractive 

 granules of the mesial region gradually become gela- 

 tinized, a group around the hilum, frequently being 

 larger, more refractive, and quite resistant. A narrow 

 refractive band at the proximal end and sides is the 

 most resistant starch ; this gradually becomes sharply 

 defined into 2 or 3 lamella? which are deeply striated but 

 not usually broken clown into linear granules previous to 

 gelatinization. The gelatinized grains are much swollen 



and distorted, the latter greater at the distal margin. 

 They do not resemble the untreated grain. 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 60 per cent of 

 the entire number of grains and 81 per cent of the total 

 starch in 3 minutes; in about 96 per cent of the grains 

 and in more than 99 per cent of the total starch in 5 

 minutes. (Chart D 223.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 1 per 

 cent of the entire number of grains and 18 per cent of 

 the total starch in 5 minutes ; in about 3 per cent of the 

 grains and 33 per cent of the total starch in 15 minutes; 

 in about 7 per cent of the grains and 64 per cent of the 

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

 grains and 71 per cent of the total starch in 45 minutes ; 

 in about 17 per cent of the grains and 78 per cent of the 

 total starch in 60 minutes. (Chart D 624.) 



Gelatinization is usually preceded by the appearance 

 of 2 clearly defined fissures which proceed from the hilum 

 and extend distalwards, sometimes meeting at the distal 

 end ; these fissures sharply define the mesial region from 

 a very refractive border. Deep irregularly arranged fis- 

 sures frequently form between these 2 fissures at the 

 distal end, especially if they are not confluent, and this 

 region is more quickly disorganized, followed later either 

 by disintegration or by gelatinization. The mesial region 

 is finally broken into an irregular mass of brilliant gran- 

 ules while the border, which extends around the proximal 

 end and sides, remains very refractive and profusely 

 striated. The grains are considerably swollen but very 

 rarely are distorted unless disintegration, followed by a 

 process of solution, is proceeding ; a very small proportion 

 of grains are completely gelatinized and a few medium- 

 sized grains are but little affected by the reagent. 



Comparison with C. rosea shows : 



Fissures proceeding from a definite hilum are much 

 more frequently demonstrable, and they form the boun- 

 dary between a much broader refractive border and a 

 mesial mass of much more refractive granules than in 

 C. rosea. The grains are much more resistant, show 

 much less distortion (practically none), and there is 

 very little disintegration, much less than in C. rosea. 



The reaction with potassium hydroxide begins in a 

 few grains immediately. Complete gelatinization occurs 

 in about 3 per cent of the entire number of grains and 

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

 per cent of the entire number of grains and 65 per cent 

 of the total starch in 15 minutes; in about 9 per cent 

 of the grains and 72 per cent of the total starch in 30 

 minutes; in about 12 per cent of the grains and 75 per 

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

 same percentage of the grains and 77 per cent of the 

 total starch in 60 minutes. (Chart D 625.) 



The hilum becomes more distinct than in those grains 

 of C. rosea in which it is demonstrable, and any fissures 

 present become wider and more extensive, and often 

 reach almost to the margin. The lamella? become very 

 distinct at first but later are obscured. Gelatinization 

 begins at the hilum which enlarges somewhat, and the 

 starch immediately surrounding it becomes divided into 

 coarse granules and the rest of the grain is covered 

 by fine stria? which become less fine and more evident as 

 gelatinization progresses, and finally as the hilum en- 



