Professor McCollum's researches, described in Chapter IX (Vitamines), have shown us that there are at least two distinct vitamines, fat-soluble A and water-soluble B. The latter is identical with the vitamine that cures beriberi. Since beriberi is a nerve disease, the water-soluble B that cures this disease is called the antineuritic vitamine.

Now the question arises, does the absence of fat-soluble A from the diet give rise to some specific disease? As early as 1913 Drs. Osborne and Mendel noticed that a deficiency of fat-soluble A in the diet of rats gives rise to a characteristic infection of the external eye, known as xerophthalmia. The progress of the disease is rapid, and if not checked, the cornea may become involved and total blindness may result. The frequency of this eye disease among rats whose diets did not include the fat-soluble A factor led Professor McCollum to the view that xerophthalmia is a direct consequence of the absence of this vitamine. This view, however, has not gone unchallenged.

Drs. Hopkins and Funk are of the opinion that rickets is the result of fat-soluble A deficiency and English schools of physiology and medicine have supported them in this view. In America this opinion has met with some opposition. This opposition really resolves itself into something like this: we do not deny that fat-soluble A is one of the causes, but we do not think that it is the only factor involved.

Fat-Soluble A And Rickets

Fat-soluble A is one of the causes of what? Of rickets. Rickets is defined by Sir William Osier as "a disease of infants, characterized by impaired nutrition of the entire body and alterations in the growing bones." Perhaps no disease commoner to infants living in the temperate zone is known. Though particularly widely distributed among the poorer classes, it is by no means uncommon among children of the well-to-do. In America children of Italian and Negro parentage are great sufferers; 90 per cent of the infants in an orphan asylum in New York were found by Dr. Hess to be suffering from rickets in one form or another.

Dr. H. Gideon Wells, the eminent Chicago pathologist, who spent some time in Roumania on behalf of the American Red Cross, relates how many of the children were stricken with eye-disease, often a very characteristic symptom when fat-soluble A is absent from the diet. For a long time the diet of the poor little unfortunate ones had consisted of corn meal and a thin bran-vegetable soup, neither of which contains any fat-soluble A. Dr. Wells finally managed to procure some codliver oil which, like butter fat, is rich in fat-soluble A. The eye disease disappeared soon after.

Anatomical Features

Glisson, an English anatomist of the seventeenth century, so accurately described the appearance of the body of a rickety child that a portion of his account may be reproduced: "The parts of the child are irregular and of unusual proportion. The head is larger than normal, and the face fatter in respect to the other parts. The external members and muscles of the body are seen to be delicate and emaciated. The whole skin, both the true and the fleshy and fatty layers, is flaccid and rather pendulous, like a loose glove, so that you think it could hold much more flesh. The joints are not firm or rigid. The chest externally is thin and much narrowed."

When a chemical analysis of rickety bones is made we always find the quantity of calcium to be unusually low. Calcium is the most characteristic element in the bone, and its low percentage in rickety children has led to the belief that an insufficient supply of calcium in the diet, or, more likely, a difficulty of utilizing the element, is an important factor in the development of the disease.

Symptoms

As for the symptoms, which usually appear before the child begins to walk, three stand out very markedly: first, an extreme sensitiveness to touch: handling the child will cause it to cry; secondly, a slight fever (100 to 102 degrees), accompanied by rather restless nights; and thirdly, profuse sweating. "The tissues become soft and flabby; the skin pale; and from a healthy, plump condition, the child becomes puny and feeble."

Conflicting Views

In the past the treatment of rickets varied with the views held regarding its etiology. One school claimed that it could be traced to poor hygienic surroundings. Naturally, with such a belief in mind, the emphasis was placed on plenty of fresh air, on sunlight, on exercise. Another school claimed that it was due to a faulty diet; the fat in the food was insufficient. This gave rise to the use of codliver oil. This oil, belonging as it does to the class of compounds known as fats, is certainly rich in fat; but we now also know that it is rich in fat-soluble A. Perhaps the value of the oil is rather due to the vitamine it contains than to its content of fat? So thought Dr. Funk. So, also, thought Dr. Mellanby, an English observer. This investigator found that dogs deprived of fat-soluble A developed rickets. He showed that animal fats were antirachitic - that is, cured rickets, whereas vegetable fats did not. You will remember that Drs. McCollum, Osborne and Mendel had proved certain animal fats to be rich in fat-soluble A, whereas vegetable fats were poor in this vitamine, and that the animal fats were far better promoters of growth than the vegetable varieties.