From the observations of Gies it appears that small doses of arsenic administered to growing rabbits caused increased growth in the bones. When administered to pregnant rabbits the young were born with both soft parts and bones larger than those of the young of rabbits of similar size. Wegner found that small doses of phosphorus given to young animals caused the epiphyseal layer of cartilage to produce dense bone instead of spongy. The periosteum also produced bone in excess, so that increased thickness resulted. In these instances the arsenic and phosphorus seem to act as direct stimulants to the bone and other tissues.

Elongation and curvature of tibia, the result of necrosis during period of growth.

Fig. 68. - Elongation and curvature of tibia, the result of necrosis during period of growth. (Paget).