MORPHOLOGY OF THE BARLEY GRAIN. 
11 
Puriewitsch 1 concedes no more power to the aleurone layer than to 
the rest of the endosperm. 
Torrey, 2 in studies of germinating maize, attributes the secretion 
of both cytase and diastase to the epithelial layer. He associates 
the enzym with the production of a definite granular substance in 
the epithelial cells the formation of which is coincident with the first 
attack upon the endosperm cells. Incidentally, he attributes the de- 
pleted layer of crushed cells, which is formed in the later stages of 
growth, to pressure and not to the absorption of the still growing 
endosperm by the expanding scutellum. 
Van Tieghem 3 finds, among many things less pertinent to this dis- 
cussion, that the embryo of Mirabilis jalapa is capable of utilizing 
macerated endosperm as a nutritive substance. 
Sachs 4 considers, except for minor details, that the relation of 
embryo to endosperm is one of parasite to host. 
Linz 5 finds that the removal of the aleurone layer of corn makes 
little difference in the dissolution of the endosperm. He concludes 
that this layer is not secretive. 
Gruss 6 finds that the scutellum of barley is able to secrete abundant 
diastase and to nourish itself upon starch supplied in place of the 
endosperm. 
Reed 7 looks upon the epithelial layer as containing the only 
secreting cells in either Zea mays or Phoenix dactylifera, but concerns 
himself mostly with the changes in nuclear and plasmic conditions. 
Brown and Escombe 8 conclude that the scutellum of barley secretes 
diastase, but that the production of cytase occurs in the aleurone layer, 
but they donot find anypower of secretion in a detached aleurone layer. 
Green 9 assigns the origin of cytase for the most part to the aleurone 
layer, but attributes the production of the greater part of the diastase 
to the scutellum. 
Brown and Morris, 10 in one of the most exhaustive investigations 
to which these questions have been subjected, find the scutellum of 
1 Puriewitsch, K. Physiologische Uritersuchungen iiber die Entleerung der Reservestoffbehalter. 
Jahrbiicher f ur Wissenschaftliche Botanik [Pringsheim], Bd. 31, Heft 1, p. 1-76, 1897. 
2 Torrey, J. C. Cytological changes accompanying the secretion of diastase. Bulletin, Torrey Botan- 
ical Club, v. 29, no. 7, p. 421-435, pi. 20, 1902. 
3 Van Tieghem, P. E. L. Recherches physiologiques sur la germination. Annales des Sciences Natu- 
relles, Botanique, s. 5, t. 17, p. 205-224, 1873. 
* Sachs, Julius von. Lectures on the Physiology of Plants. Tr. by H. Marshall Ward. Oxford, 1887, 
p. 373. 
5 Linz, F. Beitrage zur Physiologie der Keimung von Zea mais. Jahrbiicher fiir Wissenschaftliche 
Botanik [Pringsheim], Bd. 29, Heft 2, p. 318, 1896. 
6 Gruss, J. Leber die Secretion des Schildchens. Jahrbiicher fiir Wissenschaftliche Botanik [ Pringsheim], 
Bd. 30, Heft 4, p. 645-664, 1 fig., 1897. 
7 Reed, H. S. Study of the enzym-secreting cells in the seedlings of Zea mais and Phoenix dactylifera. 
Annals of Botany, v. 18, no. 70, p. 267-287, pi. 20, 1904. 
8 Brown, H. T., and Escombe, F. On the depletion of the endosperm of Hordeum vulgare during germi- 
nation. Proceedings, Royal Society, London, v. 63, no. 389, p. 3-25, pi. 1, 1898. 
9 Green, J. R. Soluble Ferments and Fermentation. Cambridge [England], 1899, p. 29, 93. ' 
10 Brown, H. T., and Morris, G. H. Researches on the germination of some of the Graminea;, part 1. 
Journal, Chemical Society [London], v. 57 (Transactions), p. 458-528, 1890. 
