THE EFFECT OF 12 PLANTS GROWING IN A COMMON HABITAT ON THE BODY-WEIGHT AND THE WEIGHT OF INTERNAL ORGANS IN THE MEADOW VOLE (MICROTUS-PENNSYLVANICUS)

Among the very abundant plants found in the habitat of the meadow vole (M. pennsylvanicus) and often used as natural food by the animal, 12 were chosen as part of the diet of subadult voles in laboratory conditions. The preferred plants were reed phalaris (Phalaris arundinacea), timothy (Phleum pratense), awnless brome-grass (Bromus inermis), Canada thistle (Cirsium arvense) and couchgrass (Agropyron repens), which correspond to stomach analyses (done previously). Diets consisting of umbellate aster (Aster umbellatus), Canada thistle, simple aster (A. simplex) and reed phalaris were the only onces causing weight loss in the animals. All diets contained a minimum of 11% crude protein and an energy value of 4.3 kcal/g of dry weight(1 kcal = 4.1868 kJ). Weights of the spleen and adrenals did not differ significantly between treated and control animals. Some diets caused significant decreases in the weight of the liver: others caused significant increases in the weight of the kidneys. Many of the diets caused both effects, a phenomenon previously recorded in experiments on food poisoning in laboratory mice. Results are discussed in relation to recent hypotheses about protoxin.