Studies of serial tangential sections of the secondary xylem indicated that increase in girth of the cambium was accomplished not by regulated divisions spaced merely to bring about the required increase in circumference, but by such rapid multiplication of initials as to produce a great superfluity if all survived. Owing to the rapid production of new initials and the associated high ratio of disappearance, the pattern of cells in the cambium changed quickly. This necessitated extensive intercellular adjustments which apparently were of rapid completion. No support was found for Priestley's theory that cell adjustments in the cambium are gradual and of a "symplastic" nature.

Synopsis Greenhouse tests indicated no reduction in the survival of Rhizobium meliloti on alfalfa seeds and in soil fertilized with ammonium sulfate treated with 2‐chloro‐6‐(trichloromethyl) pyridine. Reduction in seedling growth of alfalfa plants was severe at 20 ppm of 2‐chloro‐6‐(trichlorornethyl) pyridine and slight at 1 ppm. Other deleterious effects on alfalfa seedlings were changes in nodule morphology and deformation of root tips.

Studies of the secondary xylem and phloem indicated that after their origin in anticlinal division, sister fusiform initials usually elongated rapidly, particularly at their overlapping tips. After this first phase, rate and amount of extension varied, both along the overlap and at the opposite ends. Often elongation proceeded in a somewhat periodic fashion, being determined in part by inherent factors and in part by position and behavior of the adjoining cells. Sometimes elongating tips were temporarily stalled at blocking rays, while at other times very rapid extension occurred in association with loss of a neighboring initial from the cambium. Growth appeared to be apical, "intrusive" in the sense that the elongating tips thrust between other cells. No evidence was found to support the theory of simultaneous elongation of considerable portions of adjoining walls by "symplastic" growth.

Phalaris tuberosa var. stenoptera, P. tuberosa var. hirtiglumis, and P. coerulescens are reported to differ significantly in their degree of seedling vigor during plant establishment. To determine the relationship of carbohydrate metabolism to seedling growth and development, seeds of each species and variety were analyzed for starch, total sugars, reducing sugars, and nonreducing sugars during the first 15 days after initiation of germination in the dark. Seedling growth during the same period was also observed. Seedling growth in P. coerulescens was greater and more rapid than in the other two species. Radicle emergence in all species was closely associated with a rapid rise in sugar content. Seedling growth in the dark continued after starch exhaustion, but declined as the sugar levels in the seedlings decreased. Seedling growth rate is an important part of seedling vigor. Evidence is presented which suggests that the growth rate of hardinggrass seedlings is limited by the ability of the seedlings to use the sugars supplied by the endosperm. With perlagrass and Phalaris coerulescens, the limit appears to be in the ability of the endosperm to supply sugars.

Application of nitrogen and phosphorus to parent plants of O. miliacea increased the number of seeds produced per plant and the mean seed weight. Both the seedling growth rates and the ultimate seedling lengths in the dark independent of seed weight were increased by the fertilizer application to the parent plants. However, these increases were relatively small compared with the increases associated with seed weight. Water stress applied to the parent plants in pots, decreased the seed yield per plant and increased the mean seed weight. Seedling growth or ultimate seedling length, independent of seed weight, was not affected.