Studies in Deficiency Disease.

I.effects of varying degrees of avitaminosis on the one hand, and of ill-balance of the food on the other.Nor is this all, for pathogenic organisms present in the body, during the period of its subjection to the faulty food, contribute their share to the general morbid result.For instance, a diet deficient in vitamins and disproportionately rich in starch leads to depression of digestive and gastro- intestinal function.If, then, these organs are exposed at the same time to the action of pathogenic micro-organisms, their depression, which is at first functional, may become accentuated or fixed by organic changes due to the pathogenic agent.Further, under conditions of food deficiency, the presence in the bowel let us say of such agents may determine the character of the morbid states initiated by the food deficiency, and even impart to them endemic or epidemic characters.In these circumstances the etiological significance of the underlying food defects, which have permitted the unhampered action of the pathogenic agent, may be obscured.Experiences illustrating these points are given in succeeding chapters, but it cannot be too strongly emphasized that many of the infectious scourges to which human beings are subject such, for example, as infantile diarrhoea and tuberculosis require consideration as much from this point of view as from that of the pathogenic organism to which they are due.Other factors also, such as age, sex, individual idiosyncrasy, rate of metabolism, fatigue, cold, insanitary surroundings, overcrowding, the varying susceptibilities of different individuals, of different organs, and of the same organs in different individuals, all play a determining part in the production of the morbid result of food deficiency.So it is that in practice the manifestations of deficiency disease are influenced by a number of factors apart from the actual food fault.It may be expected, therefore, that wide variations in the incidence, the time of onset, and the character of the symptoms will occur in human beings in whom the dietetic fault has been to all appearances the same.My investigations have so far been concerned with this wider aspect of the effects of food deficiency.For I have thought it well to make a general survey of this largely unexplored territory of disease before attempting more detailed studies.Indeed, however important it is to be in a position to compare the effects of different food deficiencies in order to learn what is peculiar to any one, it is, in the present state of knowledge, of still greater importance to be aware of the extent and variety of the morbid change to which food deficiency in general may give rise, since this knowledge can at once be applied in practice.For whether these changes are the result of a peculiar deficiency or of several, they are amenable to the same remedy ; the provision of a well-balanced food of good biological value and rich in vitamins of every class.It is to this variety of morbid change that I desire to draw attention in thisNor does it appear to be the experience of the compilers of the 38^Report of the Medical Research Council,* who write : " From a consideration of dietaries consumed by the poorer classes in the towns of this country, one is led to suggest that no inconsiderable proportion of the population is existing on a food-supply more 1 Demoor and Slosse, Bull.I'Acad.