28 



the cortex there had been no collapse of cells, and that the cortical 

 cells instead of as before being longer radially, were longer tangentially 

 and had wavy membranes. 



The stronger plant shows a stage more advanced in development, 

 in that the interfascicular cambium has given rise to one or two 

 rows of cells, and more mechanical cells are present within the xylem 

 and in the fundamental tissue limiting the bundle-ring toward the 

 centre. In the phloem a few cells show membranes slightly thickened. 

 In the cortex a few cells have collapsed in 2 places, the spaces being 

 again completely filled. In other respects these 2 plants in the part 

 within the casts show all the features of the one described at the 

 period of 43 days. In both of them the vessels and xylem parenchyma 

 cells are narrower and thinner-walled than outside the cast, and the 

 corresponding cells that toward the middle of the cast have remained 

 thin-walled have nearer the upper limit of the cast become very 

 thick-walled, though the cell-diameters have not increased. 



5. 59 days after application of casts. Two plants gave upon exami- 

 nation the same results as the 2 last plants described. Within the 

 casts were no cavities either in pith or cortex, and no thick-walled 

 phloem cells. The cell-walls of both pith and cortex were wavy. 

 In the one plant where the thick-walled cells of the xylem are very 

 few within the cast the cortical cells are radially elongated; in the 

 other plant, though the cortical cells evidently were earlier radially 

 elongated, they have by growth of the bundle-ring been so crowded 

 and wrinkled that they now appear with the tangential diameter the 

 greater. 



The usual increase of mechanical tissue at the upper limit of the 

 cast was present in these 2 plants. 



With Casts applied after the Presence of a Cavity. 



In this series of experiments casts were put around 18 plants 

 that had grown to 4 internodes above the soil, the 2nd, 3rd or 4th 

 epicotyledonary internode being encased. The first examination was 

 made after the cast had been on 13 days, the last after an application 

 of 80 days. The longest interval between examinations was from the 

 36th to the 54th day. All the other intervals were ten days or less. 

 The oldest plants were 3 feet or more in height and had passed, by 

 several weeks, the blossoming time. 



Without exception this series of plants gave the same general 

 results that the first series did: Within the cast all tissues developed 

 more slowly than without, but developed continuously ; the mechanical 



