MILTONIA. 



751 



resistant than the central portion and sometimes the 

 margin on one side is less resistant than on the other. 

 The part of the grain just distal to the hiluin is usually 

 the most resistant, and this is at the last usually split into 

 2 or 3 pieces which are widely separated and then gela- 

 tinized. The gelatinized grains are very large and greatly 

 distorted, and do not retain much of the form of the 

 untreated grain. 



The reaction with chromic acid begins immediately. 

 Complete gelatinization occurs in about 9 per cent of the 

 entire number of grains and 43 per cent of the total 

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

 and 87 per cent of the total starch in 15 minutes; in 

 about 90 per cent of the grains and 99 per cent of the 

 total starch in 30 minutes; in more than 99 per cent of 

 both the grains and total starch in 45 minutes. (Chart 

 D 590.) 



The hiluin becomes very distinct and a bubble is not 

 observed to form there. The lamella; are at first distinct, 

 but later are obscured for a time, then become distinct 

 again. Gelatiuization begins at the hilura which enlarges 

 somewhat, and the grain at the same time is divided by 

 fine stria? radiating from the hilum. The starch imme- 

 diately distal to the hiluin is divided into coarse granules 

 by branching fissures, 2 or 3 of which are extended 

 to the distal margin, the surface of this part of the 

 grain at the same time assuming a pitted appearance 

 which obscures the lamellaj. From this point, three 

 methods of gelatinization may be observed. According 

 to the first method, in the less resistant grains the hiluin 

 enlarges more rapidly toward the proximal end, and the 

 starch at this point is rapidly gelatinized until only the 

 capsule remains, and this is soon dissolved and the semi- 

 fluid gelatinous material, which it has inclosed, Hows 

 out, leaving a granular mass at the distal end, which 

 slowly gelatinizes and also dissolves. The second method 

 differs from the first only in that a lamellated marginal 

 band limited on the inside by coarse granules is formed 

 about the entire margin of the grain and, as this becomes 

 uniformly thinner and more nearly transparent, the cap- 

 sule is dissolved in several places, and the remaining 

 ungelatinized starch separates into several pieces, gela- 

 tinizes, and dissolves. According to the third method the 

 lamellar structure which is obscured by fissures, becomes 

 again visible in the form of rows of granules, while the 

 space representing the enlarged hiluin is occupied by 

 irregularly placed, coarse granules which as the reaction 

 advances become more and more nearly transparent, then 

 from the hilum to within 2 or 3 lamella; of the margin 

 the whole starch of the grain rapidly gelatinizes, wliile 

 the 2 or 3 lamella; remaining form a distinct, narrow, 

 striated, marginal baud which becomes thinner and more 

 nearly transparent, especially at the distal end, and 

 finally the capsule is dissolved at this point, the gela- 

 tinized starch flows out and is dissolved, and the rest of 

 the starch at the proximal end is quickly gelatinized. 



The reaction with pyrogallic acid begins immediately. 

 Complete gelatinization occurs in about 17 per cent of 

 the grains and 50 per cent of the total starch in 5 min- 

 utes; in about 37 per cent of the grains and 72 per 

 cent of the total starch in 15 minutes; in about 59 per 

 cent of the grains and 84 per cent of the total starch 

 in 30 minutes; in about 72 per cent of the grains and 

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



82 per cent of the grains and 94 per cent of the total 

 starch in 00 minutes. (Chart D 597.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinizatiou occurs in about 67 per cent of 

 the entire number of grains and 88 per cent of the total 

 starch in 1 minute; in about 74 per cent of the grains 

 and 92 per cent of the total starch in 2 minutes; in about 

 84 per cent of the grains and 97 per cent of the total 

 starch in 5 minutes; in about 93 per cent of the grains 

 and 99 per cent of the total starch in 15 minutes; in 

 about 96 per cent of the grains and in more than 99 per 

 cent of the total starch in 30 minutes. (Chart D S'.is.) 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 97 per cent of 

 the entire number of grains and over 99 per cent of the 

 total starch in 1 minute; in all but parts of rare grains, 

 over 99 per cent of both the grains and total starch in 1 

 minute and 30 seconds; complete gelatinizatiou (100 per 

 cent) of all grains in 2 minutes. (Chart D 599.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatiuization occurs in about 84 per 

 cent of the entire number of grains and 97 per cent of 

 the total starch in 1 minute; in about 95 per cent of the 

 grains and over 99 per cent of the total starch in 2 

 minutes; all grains are completely gelatinized with the 

 exception of parts of the margin of a few; in about 99 

 per cent of the grains and in over 99 per cent of the 

 total starch in 5 minutes. (Chart D 600.) 



The hilum becomes very distinct and a rather large 

 buliMe is sometimes formed there, and if any fissures are 

 present in the untreated grain they become wider and 

 more extensive, but do not in any case extend to the 

 margin. The lamellae become very distinct and remain so 

 until the end of the reaction is nearly reached. Gela- 

 tiuization begins at the hiluin which enlarges, and the 

 bubble, if present, swells, then shrinks and disappears ; 

 and fine stria; appear radiating from the hilum through- 

 out the grain to the margin, and these become less fine 

 and more distinct as gelatiuizatiou progresses. The 

 starch just distal to the hilum is divided into coarse gran- 

 ules by irregular fissures, and the more resistant starch, 

 as the hilum enlarges and the grain swells, is pushed to 

 the margin where it forms a very distinctly lamellated 

 and striated band, the inner lamella of which is divided 

 into a regular row of granules, while just within this at 

 the distal end is the collection of coarse granules formed 

 from the material just distal to the hilum. The whole 

 marginal band and the granules become thinner and more 

 nearly transparent until finally all the iutracapsular 

 starch is gelatinized and only the thin capsule remains. 



The gelatinized grains are large and at first are not 

 much distorted except at the distal end, but later they 

 become thin-walled and considerably distorted, and do 

 not retain much of the form of the untreated grain. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 82 per 

 cent of the entire number of grains and 98 per cent of the 

 total starch in 1 minute; in about 93 per cent of the 

 grains and in over 99 per cent of the total starch in 5 

 minutes; in about 95 per cent of the grains and in over 

 99 per cent of the total starch in 10 minutes ; complete 

 gelatinization (100 per cent) in 15 minutes. (Chart 

 DG01.) 



