On the etiology of rickets / by Edward Mellanby.

  • Edward Mellanby
Date:
[1922?]
Catalogue details

Licence: In copyright

Credit: On the etiology of rickets / by Edward Mellanby. Source: Wellcome Collection.

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    any explanation which centres round deficiency of these sub¬ stances. Further experiments will have to be carried out before a definite pronouncement can be made on this point. Factors of Hygiene and their Influence on Rickets. The two factors of hygiene that influence rickets, evidence of whose action rests on a definite experimental basis, are exercise and sunlight. The evidence that infection is of any importance in this respect seems to me too meagre at present to warrant discussion. I have dealt elsew'here1 with the exercise hypothesis and Findlay’s claim13 that it is the most important factor in the etiology of rickets, and will only state here that, in my opinion, the exercise taken by a child at the ordinary period of rickets development consists of small movements ; also that this general activity depends almost entirely on its diet and not on its environment. Diet not only, therefore, has its direct action on the tissues of the body—including, from our particular point of view, the bones—but, by controlling the activity, has an indirect effect. The second factor of hygiene—namely, sunlight—has quite recently come into great prominence as the result of experimental work, and demands closer consideration. The recognition of the antirachitic action of sunlight has been gradual and is the outcome of Huidschinsky’s7 observations of the curative effect on rickets exerted by the ultra-violet rays emitted by the mercury-vapour quartz lamp. Later, he supplemented the ultra-violet ray treatment of rachitic children with sunlight, whereas Riedel8 treated cases of rickets by sunlight supple¬ mented with ultra-violet rays on sunless days. Hess and Linger9 then showed that sunlight alone is capable of bringing about curative changes in rickety bones. There is now but little doubt that it is the ultra-violet rays of sunlight which are the effective agents. Many publications have appeared recently on this subject, and the action of sunlight in stimulating calcifi¬ cation processes in bone is generally accepted. This effect on calcification of bones is of great interest, but of even greater importance is the recognition that sunlight has a much wider influence, especially in the case of animals on defective diets, for in these cases it is capable of stimulating their appetite and increasing the rate of growth and activity. Even cases of latent tetany (Sachs10) and definite tetany (Huldschinsky11) have -been cured by ultra-violet rays. It is evident, therefore, that the ultra-violet rays promote some chemical change in the body which results in profound modifi¬ cation of many activities. Since these rays have very little penetrating power it is probable that their action is on the skin, and that some powerful chemical substance is thereby liberated. Hess12 has pointed ut that the antirachitic effect of the ultra-violet rays is smaller in the case of black rats as compared with white rats. Certainly in the case of puppies with dark hair the effect of sunlight in preventing the develop¬ ment of rickets, when placed on rickets-producing diets, is, in