An experimental investigation on rickets : two lectures delivered at the Royal College of Surgeons of England / by Edward Mellanby.

  • Mellanby, Edward, Sir, 1884-1955.
Date:
1919?]
Catalogue details

Licence: In copyright

Credit: An experimental investigation on rickets : two lectures delivered at the Royal College of Surgeons of England / by Edward Mellanby. Source: Wellcome Collection.

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    The experimental methods used to detect rickets have depended on (1) X ray examination of the bones ; (2) calcium estimation of the bones after death ; (3) histological pre¬ parations of the bones. The calcium estimation of the bones has been made by Cahen and Hurtley’s modification of the oxalate method. In comparative estimations it is useful ; but, since it is well recognised that the calcium content of bones varies con¬ siderably and independently of the rachitic condition, this method can never be used alone and must always be con¬ trolled by histological examination. [In the lecture further details of the methods were described and X ray photographs and histological specimens were demonstrated by means of the epidiascope]. In these lectures I propose to illustrate the normality and degree of rickets obtained by means of the calcium oxide content of the bones. Histological preparations can be seen if desired and also the X ray photographs of many of the dogs. In all cases histological preparations of the bones were made and corresponded, in comparative experiments, with the CaO results given. [A series of puppies with and without rickets was then shown]. In the puppies exhibited it will be observed that the differences between normal and rachitic puppies are similar to the differences between normal and rachitic children. Like the rachitic child, the puppy shows abnor¬ mally large swellings at the epiphyseal ends of the bones; it has a marked rickety rosary, its tendons and ligaments are loose, the bones tend to bend, and thereby help to exaggerate the leg deformity. The amount of deformity often depends on the weight of the animal. Again, the rachitic puppy is lethargic and does not jump about; its power to run, apart from the leg deformity and before this develops, is comparatively limited ; there is, in fact, a general loss of tone of the musculature. Similarly, just as the rachitic baby is a good baby and does not cry much, so also the dog in this condition seldom barks or makes the superfluous efforts practised by the normal healthy puppy. The puppies were started on their diets after leaving the mother, the ages varying between 5 and 8 weeks, the latter being the more usual. They were kept for varying periods according to the type of experiments. In the earlier periods they were usually killed after five to six months, but as the work progressed and the diets became more rachitic this time was considerably shortened. Determination of Rachitic Dtet. Having determined to see what part diet played as a causative factor in rickets, it was necessary to get a standard diet which would always produce this condition in the experi-