56 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



than in corn starch. These lamella;, Kraenier found, become crystalloidal in character on 

 treatment with water at 60° or 65° for about an hour, and also with chromic acid, calcium 

 nitrate, saliva, and other reagents. 



The effects of these reagents upon different starches were found to be not identical. 

 Upon potato starch the first effect is to make the lamellaj more distinct; this is followed 

 by the development of the crystalloidal chai'acter of the lamellff, which is most pronounced 

 in those lamella which are colored blue with iodine; this in turn is followed by the pro- 

 duction of small tracts or channels which connect contiguous lamella>; then larger channels 

 form which are plume-like in appearance, the grain in the meanwhile swelling quite i^er- 

 ceptibly, the middle portion becoming clearer and assuming a zig-zag outline, between 

 which and the periphery a number of crystalloidal lamella; arise; the grain now becomes 

 spherical and marked by a number of concentric lamella? near the periphery, and the 

 lamellae finally rupture, followed by a gradual solution of the grain (see page 172). 



In wheat starch the development of the crystalloidal character of the lamella; is fol- 

 lowed by the formation of narrow, interrupted or contmuous, radial channels near the 

 periphery of the grain, which are sometimes connected with lamellse located near the middle 

 of the grain; the grain meanwhile swells perceptibly, the center becomes clearer, and the 

 contents are crowded into crescent-shaped halves which are still coimected at the poles; 

 the contents of each of the halves consist of crystalloidal lamella? in wliich are then produced 

 small tracts or channels connecting the contiguous lamella>, the halves in some instances 

 finally separating and slowly dissolving. The first effect of reagents upon corn starch is 

 to bring out the point of origin of growth, which becomes larger and in some cases more or 

 less zig-zag in outline ; between tliis and the periphery of the grain there arise more or less 

 interrupted or continuous radial channels, usually the latter; the crystalloidal structure 

 of the grain de\'elops slowly and is most pronounced when the grain has swollen to two or 

 tliree times its normal size. At this stage the center of the grain has become clear and 

 the point of origin of growth has become obliterated in some cases, and between it and 

 the periphery occur numerous crystalloidal lamella; similar to those observed in potato 

 starch. Finally, the peripheral layer ruptures and there is a gradual disintegration of 

 the gi'ain. Sometimes it was noted by Kraemer that the grain appears to separate into 

 as many parts as there were arms to the point of origin of growth, particularly when acted 

 upon by saliva or diastase. 



liraemer, in sunmiing up his observations, concludes: "The starch-grain consists of 

 colloidal and crystalloidal substances, these being arranged for the most part in distinct 

 and separate lamellte, that is, at the point of origin of growth, and in the alternate lamellae 

 the colloidal substance preponderates, associated with the crystalloid cellulose; whereas, 

 in the other layers the ciystalloid substance, consisting for the most part of granulosc, 

 occurs in greater proportion. As fm'ther evidence of the presence of these crystalloidal 

 and colloidal areas we may say that the peculiar behavior of the colloidal layers toward 

 aniline stains is analogous to the behavior of a section containing mucilage cells towards 

 these dyes, the latter being taken up by the mucilage cells alone." lu-aemer holds that 

 differences in the starch-grains show that starch, instead of being a uniform substance, 

 is in fact composed of several substances in varying proportions, but more or less definitely 

 arranged. 



Denniston (Trans. Wisconsin Acad. Science, Arts and Letters, 1904, xv, 664), in his 

 studies of the growth and organization of the starch-grain, also made use of aniline dyes 

 to differentiate the different layers, and he furthermore noted that the differences of the 

 various layers of the same grain vary when the grain is mounted in water, iodine solution, 

 and a solution of gentian violet and orange G, respectively. Layers which, for instance, 

 appear single in water may appear double or multiple in a color reagent, and a single layer 

 brought out by one stain may appear as two by means of another. The results of the 



