52 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



is a brief summary of Salter's results: (1) The starch-grain, in all stages of its develop- 

 ment, is sharply differentiated from the plastid in which it originates. In no instance are 

 transition lamelkc noted. The substance of the grain is separated out by protoplasm, but 

 not produced by the gradual transformation of the successive laj'ers of protoplasm. (2) 

 Meyer's obser\'ation that the chromatophore forms a complete and constant but very 

 delicate integument of the starch-grain was confirmed in many instances. (3) The stain- 

 ing reactions prove the accuracy of the \'iew that the lamellated appearance of starch- 

 grains is primarily to be ascribed to the differences in density and also to the varying 

 absorption capacity of the different layers ; and that the coloration by stains is due merely 

 to the imbibition of coloring matter between particles, the layers which stain dark being 

 comj^aratively loose and watery, the darker the staining the less the density. (4) The 

 conclusion reached by Nilgeli regarding the uniform density of the young grains, and the 

 manner of formation of the liilum and the first soft lamellae, was confirmed. (5) All grow- 

 ing grains appear to possess a dense peripheral layer, wliich gives no indication of a lamel- 

 lated structiu'e. The lamellae attain their distinguishing characteristics when covered by 

 the lamellae formed subsequently. (6) A progressive but not uniform decrease in density 

 is noted in passing from the periphery toward the hilum, or structural center of the grain. 



(7) Lamellation bears a close relationship to the diverse conditions which arise during the 

 formation of the layers. It is noted that layers soft at first become dense after a time. 



(8) Changes of the surface of the grains may be owing to ferment action. (9) Every 

 lamella consists of structural elements arranged radially. 



The substances designated a-amylose and /3-amylose by IMeyer were studied by 

 Syniewski (Annal. d. Chem. u. Phar., 1899, cccix, 282), who found that when starch-paste 

 is treated for several minutes with malt extract all of the paste is dissolved except a small 

 portion that remains as a flocculent mass, which is the amylocellulose of Meyer. According 

 to Meyer this substance, when boiled in water and again treated with malt extract, is for 

 the most part dissolved, lea\'ing a residue that is a-amylose. Syniewski ascertained in these 

 experiments that from starch-paste amylocellulose could be obtained in quantities ranging 

 from 0.7, 2.4, 3.6, and even to 13 per cent, according to the concentration of the paste; 

 and also under different conditions variable percentages from paste of equal concentration. 

 These facts led to the belief that amylocellulose is formed from the starch-substance that 

 originally is dissolved or swollen. He notes that when a 5 per cent starch-paste is heated 

 in a closed vessel under a pressure of 3 to 4 atmospheres, the starch-substance is entirely 

 dissolved. From tliis solution on cooling there separated a gelatinous mass which is insolu- 

 ble in cold water and not acted upon by diastase. On heating this mass it went into solu- 

 tion, and upon cooling it again became gelatinous, but upon frequent repetition a stage was 

 reached when not all of the gelatinous matter was dissolved upon heating. Tliis residue 

 is not soluble in hot water, and is, he states, the a-amylose of Meyer. 



Syniewski found that, from a solution which according to Mej'er contained only /3- 

 amylose he could obtain amylocellulose, and also that by continued boihng under pressure 

 he could obtain the a-amylose. Amylocellulose and a-amylose therefore, he writes, originate 

 subsequently from the substance of the starch-grains that first went into solution. When 

 malt extract was added to starch-grains suspended in water, and the imxture heated to 

 70°, the starch was found to be dissolved completely without lea^'ing any a-amylose, which 

 would necessai'ily remain if it preexisted in the starch-grain. There is, therefore, states 

 Syniewski, no evidence to uphold the theory that starch is a compound of two substances. 

 To the contrary, he holds, since the starch-substance is homogeneous at 138°, a temperature 

 not favorable for the origin of derived products, even if these by transformation go into 

 solution, that it is safe to assume that the starch-substance is a single body. By the action 

 of sodium peroxide on starch a form of soluble starch occurs which Syniewski regards as 

 the simplest structural element of the complex starch-molecule, and which he terms 



