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143 Annotations. RACIAL IMMUNITY. " Ne quid nimis." To recent issues of Man Colonel J. Cunningham, I.M.S., Director of the King Institute in Madras, has contributed a review of the factors of racial susceptibility and immunity to disease. The problem has attracted attention ever since medical men with a Western training began to move about the world and observe the differences with which the various diseases they found affected the several varieties of mankind. There are in the literature a good many statements that susceptibility to this or that infection varies with race, but only recently have workers realised the difficulties of being sure that these variations are really linked with the anatomical and physiological characters which make up racial differ- ences, rather than with the sanitary state and eircuni- stances, the habits and modes of life which normally accompany them. It is easy enough to show that, starting with a single pair of guinea-pigs, races may soon be obtained by in-breeding wdiich differ in the most detinite way in their susceptibility to inoculated tubercle. In such experiments the animals live side by side, their surroundings are identical, and they differ in nothing but their genetic constitution. But in man the world seldoni, if ever. yields us a com- parable example of two races living side by side with no signilicant difference except their inborn nature. It is, of course, obvious that the rarity of scarlet fever and the frequency of lnalaria in India tell us nothing of the relative susceptibility of English and Indians to these diseases. Nor does a direct comparison of Englishman and Indian in India give us a straight- forward answer. Beri-beri, for example, is almost unknown except in natives, and if their habit of getting a large part of their energy from decorticated rice is not the whole explanation of the incidence of the disease among them, it gives us a satisfying reason why the English living alongside them escape it altogether. Similarly, kangri cancer in Cashmir is no more truly racial than is mule-spinners’ cancer in Lancashire. It is evident that the two races living in the same country must live the same lives if valid comparisons are to be obtained. Even if super- ticially there is considerable similarity, detailed knowledge may bring to light effective differences. Of this Colonel Cunningham gives a good example in a town in Southern India, where Hindus and Mahommedans lived in the closest proximity and yet kala-azar occurred only among the latter who were traders and moved about the country, while the agricultural Hindus stayed at home where social and religious barriers prevented any close personal inter- course of one sect with the other. Similarly, it is not fair to deduce racial differences in susceptibility from a comparison of the negroes and whites in the United States without a full appreciation of the generally deteriorated position of the coloured part of the population, industrially and socially, and all the consequences which that involves. It seems likely that the almost universal occurrence of rickets in negro babies in New York is as near a racial character as can be expected, for it is no doubt largely due to their pigmented skins, which are beyond their control ; but without further investigation we cannot measure the concurrent importance of their financial and residential condition over which they and their fellows could exercise some choice. Finally, Colonel (’unningham mentions another factor of great importance which is necessarily more complicated. It is now being realised more and more that human populations, and especially dense urban populations, have come into some sort of balance with the infectious diseases to which they are exposed, partly by progres- sive selection and partly by active immunisation by 1 Man, 1926, pp. 161, 184, 199. subinfections in early life. The population of London, for example, has become as a whole resistant to measles just as the rat population of India has, during the last 30 years, become resistant to plague. If Londoners had been living in the Faroe Islands in 1846 they would not have suffered very much from the epidemic of measles which smute three-quarters of the natives. It follows that two races living together cannot be properly compared for resistance unless they have been equally selected and immunised ; in other words, their past history is germane as well as their present circumstances. Considerations of this kind may well explain the easy susceptibility of negroes to tuberculosis ; in the end they may become as resistant as the whites living with them. This effect of exposure to infection also has its influence on the parasite, though the change will generally take place much more quickly. The spirillum of a primary attack of relapsing fever is different racially from the spirillum which is obtained from a relapse in the same patient ; the parasite has adapted itself to the resistance of its host by selective breeding. The balance of an established infectious disease concerns, therefore, both parasite and host. Such are some of the difficulties which surround the solution of a most interesting problem ; they are not less than the obscurities in which most questions of human energies are involved. But if the difficulties and necessary precautions are clearly realised, there is no reason why they should not be solved. INTRACARDIAL INJECTION OF ADRENALIN. METHODS of reanimating a presumably healthy heart that has suddenly ceased to beat, as, for example, in syncope during anaesthesia, have been many and various and their multiplicity indicates the uncertainty of their results. The statistics collected by Dr. Carl Bodon, recently quoted by Dr. Harrington Sainsbury (see p. 134 of this issue of THE’ LANCET), and the experimental researches of R. Gottlieb and J. Winter on the direct injection of adrenalin into the heart itself seem to prove that this method has certain indisputable advantages over simple massage, electrical stimulation, and injec- tion of saline. A review of the whole subject by Prof. L. Manfredo 1 will interest all who have been faced with the need of reanimating a heart in a temporary state of suspended function. The stimu- lating effect of adrenalin on the heart induced Gottlieb to try this drug for the purpose and he succeeded by using intravenous injections in restoring action in rabbits poisoned by chloral, chloroform, or potassium. Practising at the same time direct massage of the heart, he reanimated even hearts which had com- pletely ceased to beat and in which heart massage and artificial respiration alone had proved ineffectual. The use of adrenalin intravenously when the heart is arrested necessitates massage of the organ in order that the drug can reach the heart itself. It will be understood that to enable concentrations of adrenalin sufficient to act as a stimulant to reach the heart, a vein near the organ must be selected for small doses, and the farther the vein is from the heart the larger must be the doses employed. G. W. Crile, by injecting 20 and 10 mg. respectively in two wounded persons who were in a state of syncope from stovaine spinal anaesthesia, and practising at the same time cardiac massage, obtained a permanent good result. The effect of adrenalin seems to be the same whether it reaches the right or left cavities, the myocardium, or the pericardial sac. The first attempts on the human subject, inspired by the experimental researches of Winter, aimed at reaching the left ventricle, but technical difficulties and theoretical ideas induced most surgeons to reach the right ventricle; it does not appear from published reports that it is of much importance which is selected. As to its precise mode of action very little definite is known. Against the old conception of Gottlieb who, from his experiments on frogs’ hearts, affirmed that 1 Archivi di Biologia, Genoa, July-August, 1926.
