1902] THE STRUCTURE OF THE STARCH aRAIN 349 



specific action on the layers. The figures of Salter, however, show 

 that the stain is taken up by certain parts of the grain more than 

 others, and in another place he states that '*die Lamellen die im 

 frischen Starkekorn als dunklere Linien erscheinen sind die- 

 jenigen welche den Farbstoff am reichlisten einsaugen." In 

 speaking of Me^^er's work he goes on to say: ''Meyer erwahnt 

 dass bei der Farbung mit Methylviolet der Farbstoff besonders 

 von den weicheren Lamellen beibehalten wird." , The only 

 unfortunate thing is that we do not know to what layers these 

 authors refer when they speak of "weicheren Lamellen" and 

 lamellae with *' dunklere Linien/' There seems to be no doubt, 

 however, that what they have in mind corresponds to my own 

 observations, that is, it is the layers which are colloidal in char- 

 acter which take up the stains; in other words, the point of 

 origin of growth and the layers alternating with it. 



Another interesting feature serving to differentiate the layers 

 of the starch grain is the behavior toward dilute iodine solutions. 

 The layers which are not affected by the aniline stains become 

 blue with Iodine, the alternate layers and the point of origin of 

 growth remaining unaffected. The layers thus affected by 

 iodine are the ones which are rich in granulose and are more 

 clearly defined in the grains of potato and wheat starch than in 

 corn starch. These layers become crystalloidal in character on 

 treatment with water at 60'' or 65"^ C, for about an hour, and 



also with chromic acid, calcium nitrate, saliva, and other 

 reagents. 5 



The behavior of potato starch toward these reagents may be 



{figs, i-io) 



{M 



followed by the development of the crystalloidal character of the 

 lamellae (y?^- j), which is most pronounced in those colored 

 blue with iodine; this is followed by the production of small 

 tracts or channels {fig. 4) connecting the contiguous lamellae, 

 particularly in the middle of the grain ; succeeding this there is 

 the formation of channels which are larger and plume-like in 

 appearance {fig, 5), the grain meanwhile swelling quite percep- 



sProc. Acad. Nat. Sci. Philadelphia 53 : 450. 1901. 



