SUMMARY OF THE MORE IMPORTANT LITERATURE UP TO 1S72. 87 



Fritzsche seems to have been the first to observe under the microscope the changes 

 which occur in starch when it is heated in water, and he states that remarkable changes 

 are seen when a thin hiyer of starch is placed between two thin glass plates and one end 

 of the plates gradually heated until the water boils. The first change observed in potato 

 starch is in the region of the liilum (referred to by Fritzsche as the Kern), where cracks 

 are formed, and at the same time the hilum begins to expand in the direction of the part 

 of the grain where the laj^ers are thinnest and where the least resistance is offered. The 

 cracks often spread out irregularly tlu'ough the grain. Then the water in which the starch 

 is placed passes into the layers of the grains and the grains spread out until all traces of 

 lamellation disappear. While these changes are going on some of the inner, now porous, 

 layers are partly dissolved and the parts undissolved float about as small flakes. If iodine 

 is added to such a preparation the flakes are colored blue, but the swollen grains take on a 

 reddish hue. He also made observations of the effects of acids and alkahes and of alcohol 

 and water. He noted the interesting phenomenon that if small quantities of water are 

 added to alcohol and the starch-grains are boiled in it, the larger the quantity of water 

 the more does the liilum enlarge, from which he concludes that the hilum is composed of 

 a peculiar substance which expands at high temperature. 



Various investigators had made elementary analyses of starch antedating this period, 

 and their figm-es were collected by Brunner (Ann. d. Phys. u. Chem., 1835, xxxiv, 319), to 

 which was added the results of his own labors. The following year Payen (Ann. de chim. 

 et phys. 1836, lxi, 355; lxv, 225) concluded, from analyses of different kinds of starch, 

 that all starches consist essentially of amidone (starch) and dextrin, and that all have the 

 same elementary composition (CeHjoOs), differing merely in their molecular constitution. 



Poggendorff (Joe. cit.) at this time, as previously stated, reviewed the most important 

 parts of the literature of the starches up to this date, and in summing up the results of 

 the several researches makes the following statement : Starch, as present in granular form in 

 the cereals, potatoes, etc., is undoubtedly an originated substance in the general sense that 

 it is a simple nutritive constituent of the plant. Raspail's view that the starch-grain is a 

 sort of a sac filled with a gum-Uke substance is held to be untenable, whereas Fritzsche's view 

 is deemed in better accord with the facts. Poggendorff WTites that he can not tell of what 

 the point or Kern, as named by Fritzsche, is composed, or what causes the layers to be sep- 

 arated during the breaking down of the grain, but that we do know with a degree of cer- 

 tainty that the layers consist only of material which we call starch (Starkemehl), and we 

 know that the insolubility of the intact grains in cold water is caused either by the fact 

 that the outermost layer has a special cohesion or that it is saturated \\ath an albuminous 

 substance by which the grains are surrounded in the cells. The former view, he states, 

 is shared by Payen, but he beheves that the outer layer is the oldest, and that the grain 

 grows by deposition within. He doubts whether starch is dissolved in either cold or hot 

 water; he considers the name amidone superfluous because it represents nothing more 

 than pure starch ; and he believes it a question as to whether the substances named ami- 

 dine and amidin soluble are constituents or products of decomposition of the grains. 



From this time (1837) until 1845 very little was recorded in the advancement of our 

 knowledge of starches in regard to their chemistry, or to the agents which break them down, or 

 to their derivatives. Mulder (Jour. f. prakt. Chemie, 1838, xv, 299) analyzed potato starch, 

 and from his results he concluded that no water is chemicaUy combined with the starch. In 

 this year Payen published his Memoire sur I'amidon (Ann. des sciences naturelles), in wliich 

 he describes the properties of starch as determined by liimself and others. 



In 1840 Jacquelain (Aim. de cliim. et phys., 1840, lxxiii, 1G7) found that on heat- 

 ing starch-paste to 150 a substance was found which is very insoluble in cold water, 

 but readily soluble in water at 70; and he notes that when it is subjected to a higher 

 temperature dextrin and glucose are formed. The reactions of starch, dextrin, and sugar 



