202 EXPERIMENT STATION RECORD. [Vol. 41 



rates out and is removed by filtering on a Biichner funnel and washing first 

 with a mixture of 1 part ether and 2 parts alcohol, then with a 1 : 1 alcohol 

 and. ether mixture, and finally with ether. The yield is said to be from 50 to 

 55 gm. of white sugar, which may be recrystallized from water or alcohol in 

 the usual way. 



The composition of starch. — I, Precipitation by colloidal iron. II, Precipi- 

 tation by iodin and electrolytes, J. ]\Ii:llanby {Jiiocluin. .four., 13 {1919), No. 

 1, pp. 28-36). — The composition of starch has been studied by means of the 

 effects produced by colloidal iron and by iodin on a solution of potato starch 

 in water. 



Precipitation of starch by colloidal iron showed that starch granulose can 

 be separated into three fractions forming 80 per cent, 9 per cent, and 11 per 

 cent, respectively, of the starch granulose. The first fraction is precipitated 

 by colloidal iron only, the second by colloidal iron and electrolytes, and the 

 third is not precipitated by colloidal iron under any conditions. 



Precipitation of starch by iodin and electrolytes showed that starch contains 

 an insoluble constituent which does not react with iodin (amyloeellulose), 

 that all the soluble constituents of starch are precipitated by iodin in the pres- 

 ence of electrolytes, and that the final fraction precipitated by iodin gives a 

 brown color with iodin. 



These results are thought to indicate that " starch contains a variety of 

 polymers varying in complexity from amylodextrin to amyloeellulose, the 

 relative quantities of dextrin and cellulose being small while the bulk of the 

 granule is composed of amylogranulose." 



Iodin was found to luiite with starch quantitatively, forming starch iodid. 

 Approximately 1.600 gm. of starch are equivalent to 127 gm. of iodin. Starch 

 iodid, however, absorbs iodin from solution so that after the equivalent point 

 is reached the amount of iodin contahied in the precipitated starch iodid is a 

 function of the amount of iodin contained in the original solution. 



Nature of the cellulose of cereal straw, E. Heuser and A. Haug (Ztsclir. 

 Angeiv. Cliem., 81 {1918), No. 39, Aufsatsteil, pp. 99, 100; No. Jfl, Aufsatsteil, pp. 

 103, 104; No. 71, Aufsatzteil, pp. 166-168; No. 73, Aufsatsteil, pp. 172-176; abs. 

 in Chem. Ab.f., 12 {1918), No. 22, p. 2^39; 13 {1919), No. 10, p. II48).— This paper 

 reports a detailed study of the determinution and properties of cellulose in 

 cereal straw, as a result of which the conclusion is drawn that the constitu- 

 tion of straw cellulose apparently corresponds to that of cotton cellulose. It 

 is strongly contaminated with a pentosan, and so modified by the usual bleach- 

 ing processes that the pulp contains considerable oxycellulose. 



Studies on enzym action. — XVII, The oxidase, peroxidase, catalase, and 

 amylase of fresh and dehydrated vegetables, K. G. Falk, G. McGuire, and E. 

 Blottnt {Jour. Biol. Chem., 38 {1919), No. 2, pp. 229-2U) •—^to. continuation of 

 the series of studies on enzym action previously noted (E. S. R., 38, p. 803), 

 an investigation is reported of the enzyms oxidase, peroxidase, catalase, and 

 amylase in extracts of fresh, air-dehydrated, and vacuum-dehydrated potatoes, 

 tomatoes, carrots, white and yellow turnips, and cabbage at different H-ion 

 concentrations. 



The extracts of the fr«^sh vegetables were prepared by straining through 

 muslin the finely ground product. The dehydrated vegetables were soaked for 

 20 minutes in the average amount of water lost on dehydration and were .then 

 ground in the meat chopper and strained. The H-ion concentration of the 

 juice was determined colorimetrically. The technique used in testing the 

 enzyms is described in detail. The results obtained may be summarized as 

 follows : 



