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POPULAR SCIENCE MONTHLY
The change from rapid to slow decline is not sudden, but gradual, as you see by the general character of this curve.
In the next slide we can see immediately that what I have asserted as true of the male is equally true of the female, although the values
which we have differ slightly in the two sexes, and there are accidental but not significant variations in this curve as in the first. Here also we observe at once an early period of rapid decline in which the rate of growth is going down and down—a period of slight decline in which, to be sure, it is going down still, but with diminished rapidity.
There is another method by which we can represent this change