Pammel — Caryopsis and Endosperm of some Grasses. 211 



conspicuous, consisting of an outer row or sometimes several 

 rows of very thick-walled cells; the walls are mucilaginous 

 and on the addition of water are rapidly converted into 

 mucilage, showing the remnant of the primary cell wall. 

 The inner part of the nucellus consists of thick-walled cells, 

 elongated and much compressed. I am not certain that the 

 thick-walled gelatinous layer is a part of the nucellus, but it 

 appears to me, however, that it belongs to the nucellus rather 

 than the testa, although Harz refers it to the testa. Not 

 having studied the development of this species, it is difficult to 

 say whether it belongs to the nucellus or to the testa. The 

 aleurone layer consists usually of a single row of cells although 

 in places there are two rows. The cells are nearly as broad 

 as long in cross section. They are much smaller than the 

 underlying starch cells. The starch cells are much thicker- 

 walled than in other species of grasses previously described 

 in this paper. The reserve material is in part cellulose. 

 The cavity is quite densely filled with small and simple starch 

 grains (PI. XIX. 3). 



Glycerin aquatica, Smith. Glyceria aquatica and G.flui- 

 lans were figured and described by Harz. 1 I had consider- 

 able difficulty in obtaining good sections of the former. In 

 Glyceria aquatica the outer cells of the caryopsis are tabular 

 in shape, the inner walls being considerably thickened. The 

 underlying parenchyma cells are tangentially elongated. The 

 outer row of the cells of the testa small. Harz states that it 

 consists of one row of enormously enlarged and thick-walled 

 cells. The remnants of the nucellus present. The cells of the 

 aleurone layer much the same as in Glyceria aquatica, a little 

 longer than broad. The starch cells are large, densely filled 

 with compound starch grains. Glyceria fluilans has essentially 

 the same structure as G. aquatica excepting that the cells of 

 the inner portion of the testa are much smaller (PI. XVII. 7). 

 In Glyceria aquatica the testa as well as the pericarp is but 

 slightly developed. The outer part of the caryopsis is dark 

 in color. The epidermal cells are comparatively thin-walled, 

 elongated and somewhat tabular. The underlying layer 



1 1. c, G. aquatica, 1300./. 178, II. — G.fluitans, 1300./. 178, III. 



