Experimental rickets / by Edward Mellanby.

  • Edward Mellanby
Date:
1921
Catalogue details

Licence: In copyright

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

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    the aetiology of rickets, this criticism will particularly appeal. My attitude, as I imagine is that of most physiologists, is to place the hereditary factor as the cause of a particular disease in the last category for investigation and to bring it into prominence only when all other explanations fail. It is quite possible that heredity may be of some importance in rickets, but it has not up to the present materially interfered with the results of these experiments so far as I have been able to observe. It is true that I have attempted to work on litters of puppies so far as was possible but results will be given and deductions made, more particularly in the earlier experiments, when no such condition holds. Work of this nature is much simpler when each animal is comparable with another animal but, on the other hand, experiments on dissimilar animals certainly lead to results which might be missed working under the more ideal conditions. Such factors, for instance, as size and weight, rate of growth and general habits of the various types of puppy, all of which, as will be seen, are of great importance in the study of rickets, stand out prominently before the investigator when, as has happened in some of the earlier experiments, any puppy which could be procured was investigated. There is also as great a difference in the weight, rate of growth, and general habits of individual children as there is in puppies, and the disease in children is the ultimate problem awaiting solution. The work to be described has been done on a very large scale involving the dieting of nearly 400 puppies, and it will be seen to include the whole problem of nutrition. A moment’s consideration would lead one acquainted with the science of dietetics to foretell the unlimited nature of a problem of this type. It is true that recent investigations of deficiency diseases such as beri-beri and scurvy have been circumscribed and yet apparently so satisfactory that it would appear that a nutritional disease may be very limited in its aetiology ; but this does not hold in rickets. In fact there is a temptation to suggest that knowledge of both beri-beri and scurvy would be greatly increased if the experimental methods were extended to include the consideration of other elements of diet and mode of life, as well as the respective vitamines involved in the diseases. This has been done to some extent by Braddon and Cooper (5) and Funk (6), and, as the result, there is evidence that carbohydrate plays a part in the development of avian polyneuritis. It may happen that, in the case of beri-beri and scurvy, as in this rickets investigation, the limited hypothesis as to their aetiology, in which only vitamines are taken into account, will have to be extended* so as to include not only other elements of nutrition but also the general metabolism. One point, which has come most prominently before my mind as the work has progressed, is the unity of a complete diet and the interdependence of the dietetic elements. This might have been expected. Knowledge has been accumulating in recent years which emphasises the importance of balanced diets, and we know that to cut out one element of the diet means not only the absence of that element, but also the ineffective action of other elements. For instance, when carbohydrates are removed from the diet, fat is
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