316Section III.D. C. Gini.
TABLE XIX.
Mortality according to season of birth {Rome, 1908-1910).
Probable number of deaths at an age X., according to season oj birth, having
made the probable number of deaths, considering the total number of offsprings,
— 1,000.
Season of
birthAge X
0-1 year1-5 years5-20 years20-40 years40-60 years
I23456
Winter ................10361054IOII10331040
Spring ...909972975919983
Summer10799759691025971
Autumn979993104710301004
is above the mean for those bom in winter, and below it for those born in
spring. Those born in autumn shew at all ages up to fifty a greater number of
survivals than those born in summer; but these differences, very marked to
begin with, gradually decrease, until at 60 years of age the number of survivals
is greater for those born in summer, leading us to believe that contrary to what
happens in the earlier period of life, mortality in later years is greater for those
born in autumn than for those born in summer.
These inferences are comfirmed by the data of Table XIX. which shews the
relative degree of mortality at different ages according to season of birth.
(12). In all the age groups, mortality for those born in winter is found to be
above, and for those born in spring below, the average. For those born in
summer the mortality appears very high in the first group from o to one year,
and usually low in later years ; for those born in autumn, on the contrary, the
mortality is below the mean for the first two age groups, and above it in
later years.
Summer and winter appear to have an entirely different kind of deleterious
influence on the organisation of the child : the unfavorable influence of summer
seems, as a rule, to possess a selective character, eliminating the weakest
organisms and allowing organisms to survive, which will afterwards shew a
mortality below the mean; the bad influence of winter, however, appears to
have a permanent character, for not only does it kill many children, but it
weakens the constitution of the survivors. This difference is explained by a
consideration of the causes of the illness and death of children during summer
and winter. In summer the danger is caused essentially by maladies of the
digestive system, which, though dangerous, usually leave no permanent weak
ness, The danger in winter is due to the graver nature of other maladies,
