164 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VI, II
attained by those engaged in studying the effects of vitamin deficiencies encourag-
ed the investigation of the effects of other deficiencies, for example, deficiency
in the mineral components of the diet, with the result that in such fields also many
observations of the greatest importance have been made which have already prov-
ed invaluable alike in clinical and in veterinary medicine.
The period of nutritional research which we are surveying had already been
heralded by isolated suggestions regarding the importance of dietetic factors other
than proteins, fats, carbohydrates and minerals salts for the maintenance of health.
Already in 1897, Eijkman had published his experiments on the production of
beriberi, which led ultimately to the discovery of the antineuritic vitamin. Hop-
kins had stated in 1906 his conviction that scurvy, rickets and probably other
states of ill-health were caused by unknown dietetic errors the nature of which
was bound up with a defective supply of obscure food components. In 1907, Hoist
and Frolich paved the way for the identification of the antiscorbutic vitamin by
producing experimental scurvy in guinea pigs. But it was not until Hopkins
had demonstrated in 1912, the fundamental importance of accessory factors in the
diet for securing normal nutrition that the idea of specific food deficiencies as a
cause of disease began to gain any general acceptance.
It is common knowledge that since Hopkins's original announcement the num-
ber of accessory food factors or vitamins generally recognised as being concerned
in animal nutrition has been steadily increasing, though not all of them have been
shown to be concerned in the production of human deficiency diseases. By the
end of the first decade of King George's reign, overwhelming evidence had been
produced to show that beriberi was produced by deficiency of the water-soluble
antineuritic vitamin, Xerophthalmia by deficiency of a fat-soluable vitamin,
rickets by deficiency of the same or a similar vitamin and scurvy by deficiency of
the water-soluble antiscorbutic vitamin. It is not possible to trace in detail sub-
sequent investigations which have led on one hand to the chemical indentification
of many of the vitamins and on the other to some understanding of their physiolo-
gical action. It must suffice to point out how such knowledge has been applied to
the prevention and treatment of disease.
In countries such as Great Britain, frank vitamin-deficiency diseases, with the
single exception of rickets, are uncommon, but there is increasing evidence that
partial deficiencies of vitamins, particularly during the period of growth, are often
responsible for sub-optimal physical development, imperfections in the structure
of bodily organs and tissues, lowered resistance to certain infective diseases and
many vague subjective and objective symptoms of ill-health. It is almost certain,
for example, that mild degrees of skeletal deformity caused by faulty feeding in
childhood help to raise maternal mortality in childbirth by increasing the mechanical
difficulties of labour. The low resistance of the teeth of large sections of our popu-
lation to decay with its many sequelae of chronic disease and ill-health is due in