Experimental Cretinism

Findly (1908) and Mellanby (1919) clearly demonstrated that rickets occurred in young animals fed on a diet containing an insufficient amount of certain substances now known as the “antirachitic vitamine.” As a result of this, the British Medical Research Committee announced that rickets is a deficiency disease due to a lack in the diet of an anti-rachitic factor. For literature up to 1923, covering the etiology of rickets with special reference to dietary deficiencies, the curative values of cod liver oil and of ultraviolet radiatlion and the importance of the salt composition of the diet in this disease, the reader is referred to the excellent reviews of Korenchevsky (1921) and of Park (1923). Inasmuch as the present report deals entirely with disturbances in the growth and calcification of the bones of young rabbits, due to causes other than dietary factors, brief mention should be made of the literature on the etiology of rickets dealing with the problem from other aspects than dietary deficiencies. Park and McClure (1919) reviewed the literature on the effects of thymus extirpation on young animals and report results of their own findings on 24 out of 75 thymectomized puppies; 19 control dogs from four different litters were used. These authors present photomicrographs of the long bones and ribs of their experimental animals and conclude that no signs of rickets appear at the junction of the cartilage and shaft, and that extirpation of the thymus does not influence growt)h or development but the possibilit,y of a retardation in development or a delayed closure in the epiphysis cannot be absolutely excluded. Park and McClure did not make chemical analyses of the calcium and phosphorus content of the blood. Relative to the influence of the pancreas on the production of rickets, Park and McClure (1919) state that “Pawlow observed pathological conditions of the skeleton in the nature of osteomalacia after various kinds of operations in the pancreas region and after the production of intestinal