GENUS DIEFFENBACHIA. 465 



Iodine Reactions. With 0.25 per cent Liigol's solution the grains color a deep blue-violet, 

 the color being deepest at the margin; with 0.125 per cent solution they color readily. This starch 

 is colored more deeplj' than the pith starch. After heating until all the grains are completelj' gelat- 

 inized, the solution is colored a weak indigo and the grains very deeply upon the addition of iodine. 

 The grains are much enlarged and the capsules very much folded and lobular, some grains appear- 

 ing as granular masses. After hoilin'T for 2 minutes the solution is colored markedly and the grain- 

 residues have a distinctly reddish ajjpearance, even without using a great excess of iodine. Most 

 grain-residues are in the form of granular masses which color red on the addition of excess of Lugol's 

 solution. 



Slainin(] ReacUons. With gentian violet the grains begin to stain in 3 minutes and after 30 min- 

 utes are fairly deeply stained. The depth of coloration is less than with the pith starch. 



With safraiiin the grains begin to stain at once and at the end of 30 minutes are deeply stained, 

 but not so deeply as the pith starch. 



Temperature Reaction. The temperature of gelatinization is 68 to 69.5 C, mean 68.75. 



Effects of Various Reagents. With chloral hydrate-iodine the reaction begins in a minute and 

 all the grains are gelatinized in 25 minutes. The hilum becomes distinct as a black spot or bubble, 

 but the lamellise disappear. All the grains are tinted a slight violet. The distal end becomes dark 

 and gelatinization begins at this point, with some irregular protru.sion. The proximal end now 

 darkens and gelatinization proceeds also from this point, the two areas ultimately meeting. Some- 

 times the grain darkens also at other points on the margin, but these rarely start to swell until 

 they are reached bj^ the areas of gelatinization which spread from the ends. Rarely gelatinization 

 proceeds from only one end. The gelatinized grains are large, particularly in the longitudinal 

 axis, and present a striking banded appearance, resembling that of an annelid worm, as already 

 described. 



Reaction with chromic acid begins in 15 seconds and all the grains are dissolved in 2 minutes. 

 The hilum and lamellae are rendered very distinct. Refractive lines extend from each side of the 

 hilum, outlining an inner portion which becomes coarseh'^ striated by longitudinal fissures starting 

 from the distal end. The lamellEe are broken up by striaj into coarse granules and the margin ap- 

 pears finely striated. The hilum swells slightly and the grain passes into solution, the solution 

 ustiallj' beginning at the distal end, which opens out, allowing the inner, semiliquid starch to flow 

 out and dissolve. The proximal end is the last to disappear. Both ends may dissolve at the same 

 time, or the grain may swell in the middle and dissolve, leaving the two ends to dissolve later. When 

 plastids are attached to the grain they separate and disappear independently. 



With pyrogallic acid reaction begins in 15 seconds and all the grains are swollen in 8 minutes. 

 The hilum and lamellae are rendered very indistinct, and from the hilum two refractive lines spread 

 out fanwise toward the distal end, outlining an inner space. The hilum swells slightly and longi- 

 tudinal fissures extend from the distal end of the grain, this end at the same time swelling somewhat. 

 The fissures extend into the interior, and these with transverse fissures cause the inner portion of 

 the grain to appear as granules arranged in rows, corresponding to the lines of the lamella", while 

 at the same time the marginal part becomes denser and finely striated. The hilum continues to 

 swell, the protrusion occurring at the distal end, the inner granular matter disappearing from this 

 end upwartl ; the margin clears later. The gelatinized grains so formed are very large, much crumpled, 

 and lol)ulated at the distal enfl. This entl is usually broader than the proximal end, which is smooth 

 and rounded, and incloses the swollen hilum. 



The reaction with ferric chloride begins in 1 to 3 minutes and all the grains are gelatinized in 

 22 minutes. The hilum becomes very distinct as a black spot or bubble. The lamellae are at first 

 indistinct. The distal end of the grain becomes gelatinous and begins to protrude, while the margin 

 becomes clearer and darker, the inner portion appearing more opaque. The lamellae become dis- 

 tinct in this central portion. The hilum swells slightly and two lines outline this central portion 

 very distinctly. This inner part becomes fissured transversely and then longitudinally, with an 

 appearance of granulation. The margin at the same time grows finely striated and denser, swelling 

 gradually progressing from the distal end. The granules gradually dissolve, followed later bj' clear- 

 ing of the margin. The hilum is usually the last to react, Ijut occasionally swells greatly at the 

 outstart of the reaction, coincidently with the swelling of the distal end of the grain, in which case 

 the central part is the last to gelatinize. The gelatinized grains are verj' large, especially longi- 

 tudinally, and much crumpled and lobulated. 



