include one year longer in the period of child mortality, being computed for the first five years of life instead of the first four. His percentages would therefore be somewhat lower if computed on the basis used in the American work.
These various data demonstrate the existence of a considerable correlation between short life (brachybioty, Karl Pearson calls it) in parent and short life in offspring. Not only is the tendency to live long inherited, but the tendency not to live long is likewise inherited.
But perhaps the reader may think they show nothing of the sort. He may fancy that the early death of a parent left the child without sufficient care, and that neglect, poverty, or some other factor of euthenics brought about the child's death. Perhaps it lacked a mother's loving attention, or perhaps the father's death removed the wage-earner of the family and the child thenceforth lacked the necessities of life.
Dr. Plœtz has pointed out75 that this objection is not valid, because the influence of the parent's death is seen to hold good even to the point where the child was too old to require any assistance. If the facts applied only to cases of early death, the supposed objection might be weighty, but the correlation exists from one end of the age-scale to the other. It is not credible that a child is going to be deprived of any necessary maternal care when its mother dies at the age of 69; the child herself was probably married long before the death of the mother. Nor is it credible that the death of the father takes bread from the child's mouth, leaving it to starve to death in the absence of a pension for widowed mothers, if the father died at 83, when the "child" herself