Experimental rickets / by Edward Mellanby.

  • Mellanby, Edward, Sir, 1884-1955.
Date:
1921
Catalogue details

Licence: In copyright

Credit: Experimental rickets / by Edward Mellanby. Source: Wellcome Collection.

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    became evident that a vitamine was bound up in the aetiology of this disease. Our knowledge of vitamines has up to the present depended upon work somewhat limited both in its nature and the number of species of animals investigated, and it was hoped that the use of the dog would not only lead to results more directly applicable to the human being, but also would afford a wider basis for consider¬ ing the part played by these substances in general nutrition. This research has centred round calcium metabolism because it is the one object upon which all experimental work on rickets can be focused with the certain knowledge that a solution of the problem will clear up the practical problem of rickets as a disease. A large amount of German research has been carried out with the idea that a deficient calcium intake alone is responsible for rickets. Even now this hypothesis meets with strong support but it will be generally admitted that experimental results on animals and clinical experience are opposed to calcium deficiency as being the main cause of rickets. The problem of deficient intake of calcium has received comparatively little consideration in this research. A sufficiency of calcium has been given in most diets, an amount, that is to say, which will afford the opportunity for the formation of abundant good bone if the other conditions are satisfactory. Whether the body can make full use of the calcium depends on several circumstances and the study of these determining circumstances forms the basis of this investigation. The material accumulated in this research is great and much of it, especially on the histological side, awaits closer examination. In the course of the work, facts bearing on other diseases have become evident and these, when more completely developed, will be published elsewhere. II. METHODS OF EXAMINATION Various methods have been employed for diagnosing and esti¬ mating the degree of severity of the rachitic condition, and it is necessary to discuss these methods, more particularly because it is sometimes difficult to correlate the results obtained by the different methods. It is true that as a general rule, a puppy, having the appearance of advanced rickets, will show on radiographic and histological examination typical signs at the ends of the long bones together with the production of osteoid tissue. In addition, also, the calcium content of the bones will be very low. On the other hand, it sometimes happens that the calcium content of the bones may be low when at no stage of the experiment have the external appearance or radiographic results revealed bad rickets. Very occasionally in such cases, there may have be'en but small external indications of the disease. The chief characteristic of rickets is the defective laying on of calcium salts in the growing bones. This has been emphasized by Pommer (3), Schmorl (4), and other German investigators. This poverty in calcium is revealed by all the methods of examination, but in different ways and at different stages of the