Pammel — Caryopsis and Endosperm of some Grasses. 215 



The adhering palet consists of several rows of thick- 

 walled cells. The epidermal cells are longer and somewhat 

 thicker-walled. The cells below are also thick-walled, pro- 

 vided with pore canals. In places the epidermal cells develop 

 into a short trichome. Underneath the thick-walled cells 

 occur several rows of thin-walled irregular parenchyma cells. 

 The pericarp follows. It consists of several rows of thick- 

 walled translucent cells, the cavity being very much reduced. 

 The testa is colored brown. The cells are tangentially 

 elongated and the cell-walls are thinner. The nucellus is 

 very much reduced excepting in the groove, where it occurs 

 as thick-walled cells. The endosperm differs in a very 

 marked degree from either that of Triticum or Secale, 

 especially the aleurone, which consists of three to four or 

 exceptionally more rows of cells. The starch cells are much 

 larger and contain large spherical or elliptical starch grains, 

 accompanied by numerous smaller ones. Small protein grains 

 abundant (PI. XVIII. 9). 



Hordeum jubalum,~L. The grain in Hordeum jubalum is 

 adherent to the palet. The epidermis consists of thick-walled 

 tangentially elongated cells, at least most of the cells are 

 longer than broad. In part the cells are developed into short 

 conical trichomes. The underlying cells are thick- walled with 

 prominent pore canals. The remainder of the adhering palet 

 consists of thin-walled cells much longer than broad. The 

 pericarp as well as the testa is but slightly developed. In 

 some cases the underlying parenchyma cells are not clearly 

 defined, or at least not evident until the specimens are 

 treated with chloral hydrate. The blackish pigment is largely 

 found in the internal part of the palet. Some of the pig- 

 ment also occurs in the pericarp and the aleurone layer. The 

 pericarp consists of one or two rows of rather thin-walled 

 tangentially elongated cells. The testa is reduced to a single 

 layer of cells somewhat longer than broad. The nucellus is 

 nearly absent except in the groove. It consists of a single 

 row of thin-walled, colorless, compressed cells. In the groove 

 several rows of cells occur. On either side of the groove 

 these soon disappear. The aleurone in the specimens studied 

 is made up of a single row of cells. The cells of the starch 



