Gilbert A. Leisman

A New Species of Cardiocarpus in Kansas Coal Balls

initial investigations of these balls that the plant fragments contained therein reflect a slightly different floral aspect than those of the West Mineral material. Although both aspects indicate a noteworthy diversity of plant groups, the cordaitean element appears to dominate the flora of the Mineral and Fleming balls while the lycopod element, if not dominant, is certainly much more abundant in the Bevier balls. This apparent floral difference is given further credence by the absence of this new species of Cardiocarpus from the Fleming and Mineral material and its

The Rate of Organic Matter Accumulation on the Sedge Mat Zones of Bogs in the Itasca State park Region of Minnesota

In any discussion of the rate of net accumulation of organic matter, a working knowledge of the various factors which influence the rates of deposition and decomposition is indispensable. It is obvious even to the most superficial observer that at least part of the organic matter deposited each year upon the earths crust must decay, otherwise the earth would long ago have been completely covered by a layer of plant and animal remains many feet thick. A survey of the world literature on this subject reveals that deposition and decomposition of organic remains rarely proceed at equal rates. In humid equatorial and tropical regions annual organic deposition is very great but decomposition is also very rapid so that no net accumulation results. In arctic regions, at the other extreme, the frost table may rise during the winter following the brief growing period when the organic layer was laid down, never to thaw again; under these circumstances annual deposition and accumulation are almost identical and decomposition may be negligible except along stream banks and on slopes strongly inclined toward the equator. In mid-latitudes, organic deposition is intermediate and the rate of decomposition varies especially with kinds of plants, and local temperature, drainage, and aeration. On humid upland surfaces, the situation may closely approach that of the moist tropics;