216 Trans. Acad. Sci. of St Louis. 



layer are large and filled with round or elliptical grains. The 

 starch cells are larger than those of the aleurone. The 

 starch grains are mostly round or somewhat elliptical (PI. 

 XVII. 6). 



Elymus canadensis, L. In Elymus canadensis and other 

 species of the genus the grain is adherent to the glume. 

 The outer part does not differ essentially from that of the 

 genus Ilordeum except that the walls of the epidermal cells 

 are not so thick. The underlying cells are thick-walled as in 

 the genus Hordeum. The pericarp consists of thick-walled 

 tangentially elongated cells with a very small cell-cavity. 

 The inner portion of the pericarp consists of a row of thinner- 

 walled cells. The testa consists of a layer of thin-walled 

 cells. The remnants of the nucellus much compressed, and 

 on the addition of chloral hydrate appear as a translucent 

 colorless layer with greatly thickened walls; the cell-cavity 

 much reduced. The aleurone consists of a single layer of 

 cells. The cells of the starch layer are much larger than the 

 aleurone and filled with spherical or elliptical starch grains 

 (PL XVIII. 4). 



BAMBUSEAE. 



Arundinaria macrosperma , Michx. The large grains of 

 this species are free. The epidermal cells of the peri- 

 carp are thick- walled and roughened. The lateral walls 

 are much thinner than the exterior. The external wall 

 is plainly stratified. The cells are marked with prominent 

 pore canals. The underlying layer consists of two to three 

 rows of very similar cells except that the walls are less 

 thickened. The internal part of the pericarp consists of one 

 to two rows of thick-walled cells with a very narrow cell- 

 cavity. The testa consists of thinner-walled cells of slightly 

 brownish color. The aleurone consists of several rows of 

 thick-walled cells. The large starch cells contain relatively 

 laro-e compound grains. The individual elements are five- to 

 six-sided (PI. XVII. 5). 



