PHENOMENA OF DIGESTIBILITY — RAW STARCHES. 183 



out, SO that the process of solution may now take place in the opposite direction — that 

 is, from the inside to the periphery. Otherwise, the behavior of potato starch is like that 

 of Phaseolus grains. The remaining cellulose skeleton shows sharp outlines at first, and 

 more or less distinct lamellse, especially in the larger grains; the cellulose skeletons appear 

 to be more substantial, and the outer layers are decidedly more dense than those in the 

 inside of the grain. The cellulose reaction with Lugol's solution is not so easily obtained 

 with the skeletons of potato starch. At first they are stained only a pale yellow, and it 

 takes 30 to 60 minutes to produce the violet reaction. The outside dense layers are less 

 easily stained than the other parts, and usually continue to show a brownish color when the 

 violet has abeady begun to appear in the inner parts. The solution of the cellulose skele- 

 tons appears to take place more rapidly here. Some grains were noticed in which one part 

 was still unchanged, while the skeleton of the other part had almost entirely dissolved. 



In the few sprouting tubers of potato examined it was found that solution seems to 

 begin in the center of the grain, and the process to go on evenly from this point, so that 

 the grain is changed into a thin-walled shell, with the inner layer of the wall indistinct. 

 These deviations are stated to be unimportant in the process of solution. 



.(EscuLus Hippo CASTANUM. 



The starch-grains of the horse-chestnut are changed outside the cell in the following 

 manner: At that part of the starch-grain farthest removed from the hilum, where the 

 otherwise not very distinct lamellse appear particularly distinct and numerous, a trans- 

 parent triangular space is developed which penetrates deeper into the inner part of the 

 grain, and reaches and surrounds the hilum; in the meanwhile, some single lamellse or 

 groups of lamellaj dissolve more quickly than others, causing the latter to appear as dark 

 cross-stripes, and also giving the grain a peculiar striated appearance. The more dense 

 and unchanged portions belong to the periphery of the grain, so that after the process of 

 solution in the inner part has sufficiently progressed, the grain floats in the solution and 

 appears like a bubble whose walls are riddled with numerous uTegular holes. Finally, 

 only isolated portions of the latter are left, which, however, retain their former position, 

 so that the outlines of the former starch-grain can still be recognized. This goes to show, 

 writes Baranetzsky, that in this case also, after the granulose has dissolved, a residue is 

 left which undoubtedly is cellulose, but which is so delicate that it is hardly visible. The 

 interstices sometimes take a violet color with Lugol's solution and sometimes remain 

 colorless. 



In the cotyledons of germinating seeds of Msculus hippocastanum, starch-grains are 

 very often found which, while unchanged on the inside, have a sort of pitted appearance 

 on their outer surface. Seen from the flat side the grains usually show a small cavity at 

 the end opposite the hilum, and from which the starch-substance has entirely disappeared. 

 Such cavities also sometimes develop on the flat side of the grain, and when seen from 

 above look clear and round. Seen from the side of the gi'ain, the contours of these cavi- 

 ties are always distinct, proving that the solvent action of the ferment is merely a super- 

 ficial one and does not penetrate into the substance of the grain. Very often conditions 

 are found in which the greater part of the grain has disappeared while the remaining 

 clearly outlined part is unchanged. How this superficial process of solution continues 

 was not determined. During germination of such seeds as those of JUsculus hippocastanum, 

 only a very small part of the grain is used up. It would therefore seem that grains which 

 so energetically resist the action of the ferment undergo no change. Usually, however, the 

 germinating seeds of the horse-chestnut dissolve from the inside, resembling the process 

 described in the grains of potato starch. The starch-grains of one and the same seeds are 

 not always affected in the same way, so that it would be necessary to examine a number 

 of seeds in order to observe typical forms of the two extremes. 



