106 Trans. Acad. Sci. of St. Louis. 



cell-walls, including the light line, color brown, and then 

 change to brownish-black, indicating cellulose. With sul- 

 phuric acid and iodine the cell-wall colors blue ; the light line 

 colors somewhat later. The elongated colorless cells below 

 also color blue. 



Rhamnaceae. Malpighian cells are not universal for the 

 order, since Ward and Dunlop (466) do not indicate them 

 for Rhamnus^ nor does Lindau (394) for this genus. 

 I did not succeed in finding these cells in Berchemia ; nor 

 does the work of Miers (411) indicate them for the seeds 

 studied by him. The material of Rhamnus at my disposal 

 was not satisfactory. Godfrin (71), who studied Zizyphus 

 vulgaris, indicates the presence of a light line in the upper 

 part of the Malpighian cells. The testa is very brittle, and it 

 is difficult to get good sections. When these are obtained it 

 is not difficult to make out a wide light line under the cuticle. 

 Godfrin compared it with that found in Leguminosae. 

 Structurally it may be compared with the light line found in 

 that order, but it responds very readily to the phloroglucin 

 test, coloring very deeply. The remainder of the cell-wall 

 colors in the same way, but perhaps somewhat less rapidly. 

 It will be seen that the cell-cavity is very much reduced in 

 these cells, and also that the pore-canals are short. The 

 cuticle and cuticularized layers are strongly developed. 



The testa of Geanothus americanus is hard and glossy. 

 The greater part consists of the elongated, thick-walled 

 Malpighian cells, which contain very little pigment. The 

 cuticle and cuticularized layers are well developed. The 

 broad light line occurs immediately under the outer lignified 

 cell-wall. On the addition of phloroglucin, the cell-walls of 

 the Malpighian cells, including the light line, color red, but 

 not so deeply as in Zizyphus. The light line colors some- 

 what more tardily than the remainder of the cell- wall. With 

 chlor-iodide of zinc the light line colors yellow at once, and 

 the remainder of the cell-wall soon follows. The color 

 changes to brownish-black. Sulphuric acid and iodine change 

 the cell-wall to a rather dark brown, the light line much 

 lighter in color. The Malpighian cells do not show the lignin 

 reaction in Adolphia calif ornica, where the light line is wide 



