96 Trans. Acad. Sci. of St. Louis. 



separate pore-canals. The pore-canals extend into the cellu- 

 lose portion of the cell-wall. The remainder of the cell-wall 

 colors blue, except the light line, when treated with chlor- 

 iodide of zinc or sulphuric acid and iodine. Such are the 

 reactions in Cassia^ Gleditschia, Aeschynomene, Mucuna, 

 Lespedeza, and many others studied. The cell- walls of the 

 osteosclerids and the sclerotic parenchyma in the nutrient 

 layer of the mature seed of Baptisia and of Cassia mary- 

 landica color blue more rapidly than the walls of Malpighian 

 cells. The cellulose of the cell-wall is slowly acted on by 

 cupric ammonia, zinc chloride, and hydrochloric acid. Sul- 

 phuric acid also causes a dissolution of the membranes. In 

 some few cases phloroglucin and hydrochloric acid show that 

 lignin is deposited at the base of the cell as well as in the 

 cuticularized layer, as in Baptisia leucophaea and B. australis. 

 The reactions are shown more clearly in Tables A and B. 



Pore-Canals and Cell-Cavity. — The Malpighian cells 

 are not uniform as to thickness ; the cell-cavity is as a rule 

 larger in the lower than in the upper end, but it may widen 

 somewhat near the light line in the upper part of the cell, as 

 in Gymnocladus and Gleditschia. In a surface section the 

 Malpighian cells are five or six-sided with a large central 

 cavity and radiating, frequently branched canals. Serial cross 

 sections show that the central cavity increases in size inward, 

 at the same time the radiating canals disappear. These 

 canals are certainly not to be compared with the folds occur- 

 ing in the petals of many flowers, as in Petunia and Pelar- 

 gonium (372), or in the leaves of Pinus (318), Aspidium 

 acideatum, and other plants (395). 



In Strophostyles paucifiorus the cell-cavity is large in a 

 seed that is about half grown. The lateral walls show some 

 thickening, more above than below, and the outer wall 

 receives deposits of cellulose at certain points, and as the seed 

 develops, more is added to these points. In a mature seed 

 these meet the cell-wall and usually a complete separation 

 from the original cell-cavity occurs. Some writers speak of 

 " Leistenfbrmige Verdickungen," a term not entirely in- 

 appropriate. The true nature of these canals may be seen in 

 sections treated with Schulze's medium, after thoroughly 



