Host-Parasite Relations In Initiation Of Infection: I. Occurrence Of Listeriosis In Arctic Mammals,With A Note On Its Possible Pathogenesis

A lemming colony maintained at Fort Churchill was examined for the possibility of the presence of L. monocytogenes in latent form, but the organism was not isolated. Following transfer of the lemmings from Churchill to Kingston, L. monocytogens was isolated. In speculation on the pathogenesis of Listerosis, the author suggests that an upset carbohydrate metabolism may be involved in the trigger mechanism. The isolation of L. monocytogenes from a seemingly ill Arctic fox caught at Fort Churchill is reported for the first time.     

Recent Gully Formation In Prairie Areas Of The Northern. Great Plains*

Abstract

Modern gully formation in the Great Plains and Southwestern United States has been attributed variously to overgrazing, farming, and climatic change. Pre-settlement prairie fires in the Northern Great Plains burned the protective vegetation so that gradients of drainageways were adjusted to more sediment than they receive today when wild fires are uncommon. Gully cutting may be an adjustment of the gradient to new conditions. Erosion caused by overgrazing today may not be different from that caused by wild grazing animals in the pre-settlement period.