PHENOMENA OF DTGESTIBTLTTY — RAW STARCHES. 185 



The starch-grains of germinating seeds of wheat were found to be variously affected, 

 so that all of the phenomena described above could be ol^scrved in them. It is worthy of 

 remark that in one and the same seed the process of solution takes place in a definite 

 way, the usual course being as follows: A concentric fissure develops at a distance from 

 the rim of the disk; in the middle of the space surrounded by this fissure a system of irreg- 

 ular, branched fissures arise, giving this portion the appearance of falling apart, while 

 the ring of the surrounding border is unbroken. The latter is absorbed in its entirety, 

 and radial stripes may frequently be noticed in it. The deviations from the usual coiu'se 

 exhibited by some grains explains the contradictions by Sachs (Botan. Zeitung., ].S()2, 

 page 147) and by Gris (Annales de science naturelles (Botanique), 1860, xiii, 110) in their 

 descriptions of the same process. Sachs's statement that the affected grains fii'st lose their 

 granulose, leaving a skeleton which becomes wine-colored when treated with iodine, could 

 not be verified. In the germinating seeds, as well as in the tests outside the cell, the iodine 

 reaction was always the same, i.e., a blue-violet color was obtained until the \'ery disap- 

 pearance of the grains. 



MiRABILIS JaLAPA. 



As is well known, these grains consist of numerous part-grains (p. 273) which separate 

 easily, and in their isolated state look like very minute spheres showing a Brownian move- 

 ment. It is hardly possible to follow the process of erosion in such grains, yet on the 

 whole it is safe to assume that they also dissolve through the action of the ferment. Their 

 contours become vague and indefinite, and the single part-grains gradually change into 

 indistinguishable dark points, which finally become invisible. In the grains or their frag- 

 ments that have not fallen into the single minute grains, the part-grains lying on the 

 periphery of the groups are affected first, while the others remain unchanged. If such 

 groups are not very large, then all their part-grains finally are changed, and the whole 

 fragment takes on the appearance of a fine, granular, semi-transparent mass. 



Oryza Sativa. 



In size and form, Baranetzky writes, these grains closely resemble those of buckwheat, 

 but show an extreme diffei-ence in their solubility, being tlie least easily affected jjy fer- 

 ments. The erosion process here appears to begin in the middle of the grain, and solution 

 takes place peripherally, the last stages in the process thus resembling those of buckwheat 

 grains. 



Baranetzky notes that close observation of the process of erosion of the grains of 

 different starches at once shows variations in their structure. In most of the starches 

 examined (bean, buckwheat, potato, and rice) erosion takes place more readily in the 

 inner layers than in the outer ones, agreeing perfectly with Nageli's the(iry on the structure 

 of the starch-gi-ain. When the soft hilum is eccentric the inner cavity usually spreads 

 toward the hilum side. In wheat starch the structure of the grain seems to be symmetrical, 

 as is shown by the concentric layers which make then- appearance as the grains dissolve, 

 the soft hilum being in the exact or mathematical center. Nevertheless, the central part 

 of round starch-grains does not dissolve as easily as the outer part. The radial canals 

 in which erosion begins usually stop at a distance from the center of the grain, final solu- 

 tion usually taking place by the gradual melting away from the outside. The greater 

 soluijility of the outer part of the grain might be due to a difference in chemical composi- 

 tion, Init the presence of cellulose could not be proved in this case, and there would be 

 no other reason for supposing any chemical modification in the granulose. 



Baranetzky records that the formation of the canals by which the ferments reach 

 the inner part of the grain is worthy of notice. The possibility alone of this formation 

 proves, he states, that not only different concentric layers, but also different parts of the 



