Or all the chronic diseases to which young children are liable, none sur passes in interest and importance the one now to be considered. The fre quency with which rickets occurs, the variety of tissues it affects, the influ ence it exercises upon the course and termination of intercurrent maladies, and the distressing and often fatal consequences which its presence involves render this disease especially deserving of careful study.
Although dissimilar in many respects from the class of so-called dia thetic diSeases, viz., those which arise as a consequence of a distinct con: stitutional predisposition, rickets is yet a general affection, for it impairs the nutrition of the whole body. Under its influence growth and develop ment are arrested, dentition is retarded, the bones soften and become deformed, the muscles and ligaments waste, and in fatal cases alterations are often noticed in the brain, liver, spleen, and lymphatic glands. The disease usually begins in infancy. It is rare under the age of six months, for it seems very doubtful if the cases of so-called congenital rickets are true examples of the disease. At the eighth month, however, it begins to be common, and from that age until the eighteenth month may be readily set up under the influence of causes which interfere with digestion and im pede the assimilation of food. It is less common for the disease to develop in children who have been in good health up to the age of eighteen months, but it may occur at any time between that age and the seventh year, or even in still older subjects. Although beginning at a very early age, the disease often continues for several years, and may be seen existing in a marked degree in children three or four years old.
Causation. —Rickets is the direct consequence of malnutrition in early life. Its causes Must therefore be looked for in all the diverse agencies which impair the nutrition of the growing frame. The most important of these are, no doubt, faults of feeding and hygiene. Insufficient or unsuit able food stints the body of necessary nourishment, and an inadequate supply of fresh air renders assimilation defective and weakens digestive power. These two causes are most commonly found united in the poorer
quarters of large cities. An infant who lives amongst other children in one small room, where it breathes a tainted air and derives its only nour ishment from the watery breast-milk of a weakly mother, with the addi tion, perhaps, of a little gruel or sopped bread to quiet it when it cries, can only escape rickets by becoming tubercular. By such means an extreme de gree of the malady will probably be produced. But similar agencies, al though operating in a milder form, will produce rickets in any condition of life. It is not uncommon to meet with examples of the disease in well to-do families where the child has been kept in-doors for fear of his catch ing cold, and has been supplied with farinaceous compounds largely beyond his powers of digestion. Over-feeding with starchy foods is a fruitful cause of rickets. The giving of farinaceous matters in excess, or at a time when the glandular secretions are insufficient for its digestion, is the com monest fault committed in the hand-feeding of infants. Dr. Buchanan Baxter, who tabulated one hundred and twenty consecutive cases of rickets, found that in many of them the disease dated from the time when farinaceous food was first given. It is probable that in these cases the oc currence of malnutrition and subsequent rickets is due not so much to the excess of starch as to the absence of the more nutritious food for which the starch has been substituted. Rickety children so fed are often fat, and do not, to the inexperienced eye, convey the impression of being under-nourished. Examination, however, discovers that they are by no means strong in proportion to their size. Although stout they are weak, often excessively feeble ; and it is evident that the plumpness of the child is clue to disproportionate development of the subcutaneous fat. This tissue has been enormously over-nourished while the rest of the body has been stinted and starved.