1902] THE STRUCTURE OF THE STARCH GRAIN 351 



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formation of narrow, interrupted or continuous, radial channels 

 near the periphery of the grain [fig-ij), which are sometimes 

 connected with lamellae occurring near the middle of the grain ; 

 the grain meanwhile swells quite perceptibly, the center becomes 

 clearer [fig. 14), the contents are crowded into crescent-shaped 

 halves which are still slightly connected at the poles [figs. 15- 

 17) ; the contents of each of the halves of the grain consist of 

 crystalloidal lamellae in which are then produced small tracts or 

 channels connecting the contiguous lamellae [fig, 17)) the 

 halves in some instances finally separating and slowly dissolving 

 {figs. 18-20). In some cases, on the other hand, there is a 

 corrosion of the grain at the periphery, followed by gradual dis- 



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the latter becomes larger and in some cases more or less zigzag 

 {.fig^ -^i) in outline ; between this and the periphery of the grain 

 arise more or less interrupted or continuous radial channels 

 usually the latter); the crystalloidal structure of this grain 

 develops slowly and is most pronounced when the grain has 

 swollen to two or three times its normal size; at this stage we 

 find that the center of the grain has become clear and the point 

 of origin of growth has become obliterated in some cases [fig. 

 24), and between it and the periphery occur numerous crystal- 

 loidial lamellae similar to those observed in the potato starch; 

 finally the peripheral layer ruptures and there is a gradual dis- 

 integration of the grain {figs, 26, 30,33). Sometimes the grain 

 appears to separate into as many parts as there were arms to the 

 point of origin of growth {figs. 27, 28,34), particularly 

 acted upon by saliva or diastase. 



A number of authors since the time of Nageli have shown 

 that the lamellae of starch grains differ in constitution and 

 structure, and that there are at least two distinct kinds of 

 lamellae. This view is confirmed not only by a microphysical 

 examination of the grain, and by treatment with weak solutions 



when 



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