In 1919 Mellanby (9) reported experiments which excited great enthusiasm among investigators of nutrition problems. He was able to show that certain diets produced a condition of the bones of young puppies which he believed to be identical with rickets in the human being. Radiographs showed a decrease in the density of the bones. The ends of the shafts were cupped and much enlarged and were more or less ragged in appearance. The translucent (to X-rays) area between the shaft and the center of ossification in the head of the bones was increased in depth. Mellanby regarded rontgenograms of this sort as sufficient evidence of rickets. As will be made clear later the radiograph only shows that the bones were not normally developed, but gives no information concerning the exact nature of the lesion such as can be learned only by histological examination of stained sections. The most striking point brought out by his experiments was the protective function of butter fat and cod liver oil in preventing the development of rickets or some similar condition. One diet which produced rickets in pups was composed of skimmed milk 175 c.c; white bread ad libitum; linseed oil 10 c.c; yeast 10 grams, and common salt 1-2 grams. The addition of 10-20 grams of butter served to so improve the nutrition of the animals that rickets did not develop. Mellanby drew the conclusion from his studies, that such fats as furnish fat-soluble A are protective against rickets, whereas vegetable fats which do not contain appreciable amounts of this substance, are of little value in this respect. He was therefore inclined to identify the fat-soluble A, or some substance having a similar distribution, as a specific anti-rachitic substance.

Mellanby compared two diets which Ferguson (2) had described as typical of rachitic and of non-rachitic families respectively in Glasgow. These are so instructive that they are reproduced here in tabular form. It will be evident to anyone who has become familiar with the specific dietary properties of the individual food-stuffs and with the nutritive requirements of an animal with respect to calcium, phosphorus and fat-soluble A, and with the importance of having proteins of high biological value, that one is not justified in interpreting the results of restricting human beings or animals to one or the other of these two types of diets, as turning upon their content of fat-soluble A, or similar substance which might play an important role in the etiology of rickets.

Average Consumption Per "Man" Per Day Of The Chief Articles Of Diet In Grams

(1) rachitic families. (2) non-rachitic families.