86 JOURNAL OF THE [Julyr 



the thickness of the cell wall until these cells resemble perfectly 

 those of the parenchyma of the phloem. In case of the com- 

 mingling of the elements in this way groups of cells are moved 

 from the cortical sheath, and in the phloem occasionally they 

 undergo sclerosis. In the dermatogen is found but a single uni- 

 seriate zone. Growth continues apparently during the first year 

 onl)*, when life is cut off by the completion of the first layer of 

 cork. Many of the cells are prolonged into hair-like trichomes, 

 which probably assist the stoma in supplying the plant with air. 

 No intercellular spaces occur save where stomata are formed. The 

 cells are nearly rectangular, their superficial walls being much 

 thickened and completely cutinized. They contain colorless 

 granules and sap, starch however being found in the guard cells 

 of the stoma (Fig. 22). With the formation of the cork a 

 change occurs in those cells below the stoma in or near the meris- 

 tem. As the cork is formed these cells exceed the growth of the 

 periderm, and thus is formed a double convex swelling which 

 pushes up the stoma long before death ensues (Fig. 23). At the 

 phelloderm the cells are regularly arranged in rows containing a 

 few granules and filled with a colorless sap. Outside of these are 

 the complementary cells, with corners more or less rounded, and 

 in structure similar to the cork. As in the cork, some are filled 

 with the dried remains of cell life, but, being irregularly placed 

 among the transparent cells, they present a mottled rather than a 

 banded structure. This mass of loose complementary tissue is 

 held together by 'layers of flat cells which alternate with them. 

 These tabular cells adhere strongly by their radial walls, but,, 

 owing to their irregular tangential surfaces, they do not interfere 

 with the access of air to the phelloderm. These Cortical pores 

 increase with the dilatation of the periderm, attaining in trans- 

 verse dianieter a length of five or six millimetres. The lenticles 

 of the older stems are abundant and apparently exceed the 

 stoma of the younge-r growths, and it seems not improbable that 

 they are often formed under the trichomes which thickly beset 

 the epidermis. In looking over the literature on the Wistaria, 

 as noted in the Botanischer Jahresbericht, I find only incidental 

 references made to it, as already noted. Both De Bary and Sachs, 

 in their "Handbook of Physiological Botany," nelying largely on 

 the examinations of Eichler, Criiger, and Muller, place the origin 



