PHENOMENA OF DIGESTIBILITY — RAW STARCHES. 187 



which were studied the alterations of starches of various kinds in situ and in vitro. The 

 following data are from Krabbe's article: 



Triticum Sativum var. Vulgare. 



During the process of erosion of the starch-grains of wheat, wedge-shaped and coni- 

 cal indentations are formed with their bases turned toward the circumference of the grain. 

 They are distinguished from the rest of the substance by their weaker refractive power, 

 and when seen in profile appear to have more or less dense lamelhe, which can not be seen 

 in the intact grain. These indentations are in reality pore-canals of unequal length pene- 

 trating to the center of the grain. The formation and successive lengthening of these 

 canals is not caused by the dissolving action of the diastase, as is proved by the distinct 

 outlines of the pores in all stages of development. The starch-substance remains unchanged 

 during the formation of the canals; swelling agents and iodine affected the eroded grain 

 the same as the intact one. Ferments therefore can not penetrate into the intercellular 

 spaces of the starch-grain, and there can be no question of their dissolving action. As the 

 pore-canals lengthen they usually become branched, thus setting up intercommunication 

 at various places in the cell. Observation proves that these canals originate in the outer 

 surface of the grain, the canals within the grain being secondary branches of older canals 

 which have an opening on the outside of the grain. Superficial observation of grains about 

 to dissolve often revealed some grains which looked as though large portions of the cir- 

 cumference had been absorbed, but closer examination showed that this appearance is 

 due to the same factors which cause the formation of the pore-canals, and not to the action 

 of the ferment. In cross-section the wedge-shaped and conical canals on the circumference 

 of the grains are at first circular, but as they widen they become elliptical. This is due 

 to the lateral merging of two hitherto parallel pores, a phenomenon which can be observed 

 in all its stages in the starch-grains of Triticum. In consequence of this, fissures from the 

 periphery of the grain, encircling about one-third of the circumference, give rise to the 

 mistaken supposition that erosion had taken place here. There were evidently such starch- 

 grains, in which similar coalescence had taken place, which led Baranetzky to the erroneous 

 conclusion that the diastatic ferment penetrates the starch-substance and acts as a dis- 

 solving agent. 



Other phenomena may be observed in Triticum, which also might lead to incorrect 

 inferences. In some grains passages running parallel to the concentric layers arise which 

 look as though they had their origin in the inner part of the grain without regard to the 

 outside of the grain, but it can be seen that these passages communicate with openings 

 on the outer surface. The origin of these spaces can be traced to ferment passages which 

 come from outside. Since these latter are capable of entering the grain in all directions, 

 it will not be surprising to find now and then some of these passages running parallel 

 to the concentric lamellae. Thus the different manifestations in processes of erosion 

 in Triticum depend primarily on the width, the branching, and the manner of inter- 

 communication of the pore-canals, and in a measure on the unequal distribution of the 

 pore-canals in the eroded grain. As a rule, the pores on the margin develop earlier and in 

 greater numbers on the flat side of the grain, but any number of variations from this rule 

 may occur; and it is easy to conceive that the unequal arrangement and distribution of 

 the pores in different grains can produce widely deviating characteristics in the process 

 of erosion. 



HoRDEUM Vulgare and Secale Cereale. 



The process of erosion is similar to that in Triticum. No appearance of diastase 

 penetrating the substance could be determined; and the very distinct outlines of the 

 pore-canals and the rarer occurrence of lateral coalescence of pores than in Triticum 

 confirm the theory that diastase does not act in the manner of dilute acids. 



