The effects of the seasons upon the death-rate is readily seen in a comparison of the mortality tables for countries at different latitudes. In extreme northern countries the heaviest death-rate is found in the winter and the lightest in the summer. In southern countries, on the other hand, as, for instance, Italy, the greatest mortality is found in the summer months, with a second rise in the winter, the lowest rate occurring in the more equable months of spring and autumn. Those countries which are located midway between these extremes show a maximum death-rate in the late winter and another tendency to rise in the summer. In the United States the late winter and early spring take the heaviest toll of human life. Taking ioo as the average, the maximum is reached in March, with 103'6. The difference between this and the summer months would be even more marked than it is were it not for the tremendous increase in infant mortality during the heated term, which, by a rate of 104 for babies under one year, brings up the general August rate to 82'9. Those years in which the winter is warmer than usual, and the summer cooler, are the ones which bring down the death-rate. Con siderable variation is often evident from year to year, occasioned by the causes already mentioned ; but, if longer periods are compared, the tendency to uniformity which is so evident in statistics becomes more conspicuous.
It is a noticeable fact that different ages are affected differently by the extremes of temperature. For instance, very young infants are, as a class, most carefully protected against cold, and consequently do not contribute a proportional quota to those dying in the winter. As soon, however, as they arrive at an age when this protection is no longer given, their weaker organisms render them more susceptible to the rigours of winter than are adults, and they die in large numbers in the cold weather. As they grow older resistance increases, and between the ages of 20 and 40 years the changes of temperature have little effect on the death-rate. Old people, again, become sensitive to cold ; and the summer is the most favourable time for them, even when the heat is considerable. In southern countries the children between the ages of one and five years suffer from the heat to the same extent as do their northern cousins from the cold, and then gradually acquire resistance to it.
In considering the comparative death-rate of the two sexes, we find it higher for men in practically every case. The discrepancy between the two rates varies under different conditions in different countries. Thus in Italy, Holland, France, Denmark, and Ireland, where the women to a considerable extent share the labour of the men, and are more nearly exposed to the same dangers and hardships, the female death-rate is between 93 and 96 per cent. of that of the male ; whereas in Great Britain, where the women are less exposed, the female death-rate is but SS per cent. of the male
death-rate.
The most constant and pronounced variations in the death-rate, how ever, are those due to difference in age. Notwithstanding all the efforts which have been made in all civilised countries during the last decade to reduce the infant mortality, the death-rate continues to claim its' highest figures among infants under one year of age. Wherever a strikingly high general death-rate is found, it will, upon examination, be noted that babies of this age contribute vastly more than their proportional quota to the number of deaths. Countries and localities differ widely in the extent of this infant mortality, and this difference forms a pretty accurate index to their relative merits as regards sanitation and healthful conditions of living. The highest rate is found in Bavaria—namely, 306 ; and from this appalling figure, almost equalled by European Russia and West Austria, we find the rest of Europe grading down : Italy, 214 ; Prussia, 212 ; Holland, 203 ; France, 166 ; Great Britain, 145 ; Denmark, 138 ; Sweden, 130 ; Norway, 104 ; and Ireland, 97. The low rate in Ireland has been attributed to the rarity of artificially fed babies in that country.
The United States, by the census of 1900, has about the same infant death-rate as France ; but, owing to the much less complete returns of the infant population, there is no doubt that the figures given are higher than the actual facts warrant, could they be secured in complete form. Even the figures that we have, however, are not without encouragement when com pared with those of the former census, since they show a decrease of 404 per thousand in the deaths of infants under one year of age. Much has been accomplished in the past ten years, and, with the growing conviction both here and in other countries that the infantile death-rate is a matter of grave public and private concern, much more will undoubtedly be achieved in the next ten years to come. The causes of the high rate are not difficult to ascertain, and many of them are remediable. Undoubtedly improper feeding is the most important ; and to this may he added prematurity of birth, congenital defects, hereditary tendencies, infanticide, accident, and insurance of infants. As might be expected, the infantile mortality is greatest in cities and towns, owing to the greater prevalence there of crowded and unsanitary conditions, the spread of contagious conditions, the drimkenness and vice of parents, and the employment of mothers away from the homes. Statistics show that the infant death-rate is highest among the poor classes, and lowest among the professional and commercial class. An excessive mortality among illegitimate infants is everywhere observed. In some parts of Bavaria, in the years between 1867 and 1869, as many as 70 or 75 per cent. of illegitimate children died during the first year, a death-rate of 700 or 750 per thousand.