48 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



starch is allowed to soak at 70, and the soaked grains are treated for several minutes with 

 cold saliva, skeletons are obtained which no longer color blue with iodine, and which, at 

 least in part, must consist of a-amylose, because the a-amylose could hardly be formed in 

 so short a time from the solid crystals by the action of the saliva. He believes that it must 

 therefore be assumed that a-amylose is present from the beginning in varying quantities 

 in many gi'ains. Meyer goes on to state that the results of the experiments made up to 

 that time do not show clearly the relationsliip of a-amylose to /3-amylose; that it seems to 

 him that the differences between the substances are insignificant ; and that the future may 

 show that they are merely hydrous and anhydrous forms of the same body. 



fi-Aviylose. Meyer found that when starch-grains are subjected in water to a temper- 

 ature of 138 there is obtained an apparently uniform solution of amylose, since at this 

 temperature a-amylose goes into solution as j8-amylose. On cooling this solution, amylose 

 separates from its solution in very small microscopic, viscous droplets, which do not mix 

 with water below 138, and wliich can only be regarded as a solution of water in amylose. 

 This watei'-amylose solution can be produced at the swelling temperature of starch-grains, 

 that is, at 60 to 70, at which temperature the trichites of /3-amylose are changed into drop- 

 lets of viscous solution, while a-amylose apparently remains unchanged. The trichites of 

 a-amylose are so minute, he states, that they can not be seen singly, but they may become 

 visible by fusion of a number of individuals in the form of a droplet. /3-amylose is insoluble 

 in water at a temperature of 30 or below. At 60 the crystallized /3-amylose in small 

 quantity forms a thick solution. At 100 it requires more than half its weight of water 

 to pass from the crystallized to the liquid state. 



Amylodextrin. Meyer states that this substance is of great interest because it is 

 present in grains of starch which are colored red with iodine. Grains which color blue 

 with iodine can readily be transformed into pseudomorphs consisting of amylodextrin. 

 Amylodextrin was prepared by Meyer by the action of acids upon starch, 200 grams of 

 starch in 2 liters of water and 8 grams of oxalic acid being heated to 100. The unchanged 

 amylose is allowed to settle by setting the preparation aside for 12 hours. The filtrate 

 which is rich in amylodextrin is then concentrated and frozen to remove the amylose, 

 and finally the amylodextrin solution is greatly concentrated, from which, upon standing, 

 spherocrystals of amylodextrin separate. By recrystallization and washing with alcohol, 

 a preparation is obtained which colors a pure red with iodine. The quantity of amylo- 

 dextrin produced by this method was not very great, being only about 2 per cent of the 

 amount of starch. Amylodextrin he found to be difficultly soluble in water (at 8, 0.13 

 per cent; at 30, 1.58; at 6, 3.98; at 70, 4.66; at 80, 9.33; at 90 a dense solution that 

 could not be filtered) . It is soluble in 50 per cent boiling alcohol, and more soluble in acid 

 and saline solution than in water. 



Meyer also studied the growth of the starch-grains and the relations of the grain 

 to the chromatophore. He states from the results of his researches that he is convinced 

 that the substance of the chromatophore, whether it be chloroplast, cliromoplast, or leuco- 

 plast, incloses the starch-grain as long as it lies witliin the lining cell, and that during no 

 period of its existence does the starch-grain come in direct contact with the cytoplasm. 

 The complete inclosure of the starch-grain by the substance of the starch-builder permits 

 a direct influence of the latter on the grain, because every part of the grain is in contact 

 with the mother substance. The cliloroplast appeared to be a more or less viscous droplet 

 of a colorless or light-yellow substance {stro?na), in which was a viscous droplet (grana) 

 of a substance colored dark-green with chlorophyl. In the stroma there may also be 

 present well-formed crystals of protein and also starch-grains. In his earlier experiments, 

 Meyer found difficulty in determining whether the stroma is colorless or a very light green, 

 but he now expresses his conviction that the stroma contains no chlorophyl, that it is 

 usually colorless, and seldom yellowish. In the leucoplasts of Pellionia, and in the "turned- 



