SUMMARY 1. Paralysis, produced in young male rats by avulsion of peripheral nerves, resulted in a highly significant reduction in the total weight, ash weight, ash percentage, X-ray density and bending moment at the breaking point, of the bones of the affected limb. The breaking stress was significantly reduced, but Young's modulus of elasticity was unaltered. 2. Certain of these changes were modified by treatment with sex hormones. Both oestradiol and testosterone significantly reduced the difference between the bones of the normal and paralysed limbs in respect of total weight, ash weight and bending moment at the breaking point. 3. Treatment with oestradiol significantly increased both the ash percentage and Young's modulus of elasticity, the increase affecting equally the bones of the normal and paralysed limbs. Testosterone treatment did not significantly affect either of these properties, and neither hormone affected the breaking stress.
1. Paralysis caused by anterior nerve root section, or by peripheral nerve section, leads to marked changes in the bones and muscles of the affected limb in experimental animals. Vascular changes are not the cause of the bone atrophy in a paralysed limb. 2. The altered properties of the bones of a paralysed limb are due almost entirely to a loss in the quantity of bone; bone quality is only slightly altered. 3. The bone changes that follow paralysis are due to the secondary loss of muscular activity. No evidence could be obtained that nerves exert any specific, trophic influence on bone.
The effect of lowered body temperature on histamine‐induced gastric secretion in the cat has been studied. Both the acidity and the volume of the juice fell rapidly on cooling the animal, a 15° C. reduction in temperature reducing acid secretion by about three‐quarters. The free acid content of the juice tended to be reduced to a greater extent than the volume, that is, there is a change in the composition of the juice as the animal's temperature is lowered. On rewarming, secretion recovered, though less rapidly than it fell off during cooling.
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