12 BULLETIlSr 183^ U. S. DEPAETMENT OF AGKICULTUEE. 



barley capable of converting certain starches supplied in the place of 

 its endosperm. They find that excised embryos are able to grow 

 when the scutellum surface is grafted on endosperms in which life 

 is extinct. They consider the endosperm no longer a vital tissue 

 and claim that the aleurone layer does not secrete enzyms, assigning 

 cj^tase, as well as diastase, to the scutellum. 



Ling ^ supports Griiss, as opposed to Brown and Morris, regarding 

 the extent of the dissolution of cell walls in conversion. The latter 

 attribute the ''mealiness" of nialt to a marked dissolution of the 

 cell walls. Griiss holds that the walls become merely transparent. 

 Ling finds the walls present in all parts of the endosperm, although 

 affected by cytasc. 



Vines,^ while working with yeast and agarics, assumes that similar 

 enzyms exist in other plants. He finds two classes of enzyms: (1) 

 Those that peptonize and (2) those that peptolyse. 



Be aven,^ while only incidental to the subject of his paper, remarks 

 that the starch endosperm of barley is built up in centrifugal order 

 and that its outer layer is easily broken down. 



Gibbs.^ states that in the Alsinoidese the greatly reduced endo- 

 sperm is active only as an absorptive organ of the food material 

 which is here stored in the perisperm. 



EUrodt ^ finds that small-berried malts give a higher diastatic 

 power per gram of original material than do large-berried ones. 



Brown ^ finds that the semipermeable membrane exercises a 

 selective action, allowing water to enter the grain, but absolutely 

 excluding most substances in aqueous solutions. The absorption 

 is uniform in all parts of the grain. 



SOURCE OF DIASTATIC FERMENTS. 



On account of the fact that starch is the form in which most of the 

 convertible material is stored, its digestion has received a gTeat 

 amount of attention. The process has been ascribed to tlu'ee sources: 

 (1) To a secretion of the endosperm itself; (2) to a secretion by the 

 aleurone layer; and (3) to a secretion by the scutellum. 



The theory of the self-digestion of the starch endosperm has been 

 conspicuously championed by only two men, namely, Hansteen ^ 



1 Ling, A. Presence of cell walls in the endosperm of malts. (Abstract.) Brewers' Journal [New York] 

 V. 29, no. 10, p. 440, 1905. 



2 Vines, S. H. Proteases of plants. Annals of Botany, v. IS, no. 70, p. 289-317, 1904. 



3 Beaven, E. S. Varieties of barley. Journal, Federated Institute of Brewing, v. S, no. 5, p. 542-600, 

 12 fig., 1902. 



* Gibbs, L. S. Notes on the development and structure of the seeds in Alsinoidese. Amials of Botany, 

 V. 21, no. 81, p. 25-65, 4 fig., pi. 5-<5, 1907. Abstract in Botanical Gazette, v. 43, no. 5, p. 349-350, 1907. 



^ Elh-odt, G. Unterschied des Diastasegehaltes von Malzen aus grosskomigen und kleinkomigen Gersten. 

 Wochenschrift fur Brauerei, Jahrg. 23, no. 20, p. 243-244, 1906: also in Zeitschrift fiir Spiritusindustrie, 

 Jahrg. 29, no. 23, p. 209-210. Abstract in American Brewers' Review, v. 20, no. 7, p. 379, 1906. 



« Brown, A. J. On the existence of a semipermeable membrane inclosing the seeds of some of the Gram 

 ineae. Annals of Botany, v. 21, no. 81, p. 79-87, 1907. 



' Hansteen, Barthold. Ueber die Ursachen der Entleerung der Reservestofle aus Samen. Flora, 

 Bd. 79, p. 419Hi29, 1894. 



