File:The problem of age, growth, and death; a study of cytomorphosis, based on lectures at the Lowell Institute, March 1907 (1908) (14591976420).jpg

Identifier: problemofagegrow1908mino (find matches)
Title: The problem of age, growth, and death; a study of cytomorphosis, based on lectures at the Lowell Institute, March 1907
Year: 1908 (1900s)
Authors: Minot, Charles Sedgwick, 1852-1914
Subjects: Old age Growth Death Aging Growth Death
Publisher: New York, Putnam
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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is not very large. It means simplythat there was not a sufficiently large number ofanimals measured to give an absolutely even andregular set of averages. But the general course ofthe curve is very instructive. In the earlier conditionof the young guinea-pig there is a rapid decline; inthe later, a slow decline. The change from rapid toslow decline is not sudden, but gradual, as you seeby the general character of this curve. In the next slide (Fig. 29) we can see immediatelythat what I have asserted as true of the male is equallytrue of the female, althouorh the values which we havediffer slightly in the two sexes, and there are accidentalbut not significant variations in this curve as in thefirst. Here also we observe at once an early period ofrapid decline in which the rate of growth is goingdown and down—a period of slight decline in which, 96 AGE, GROWTH, AND DEATH to be sure, it is going down still, but with diminishedrapidity. There is another method by which we can represent
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Pe/UjemjtcL^ Joa/yie/me/n^. J^rrui/e<) 2 5811 n 23 29 3S3e +5 60 75 90 105 IZO 135 ISO 165 ISO I9S 2IOi:^a^ Fig. 29. Curve Showing the Daily Percentage Increments in WeightOF Female Guinea-pigs. this change in the rate of growth which will perhapshelp to illustrate it; and in the next of our pictures(Fig. 30) we see this other form of representation.The first vertical line represents the length of timewhich it takes a young male guinea-pig to add ten percent, to its weight the first time. Here the thirdtime—the fourth—the fifth—and you see as it isgrowing older and older it takes the animal longerand longer to add ten per cent, to its weight. Finallywe get to the nineteenth addition, and we see thatthe period is very long indeed. How long thatperiod is we can judge by the figures upon the left,which represent the length of the periods in days. THE RATE OF GROWTH 97 From the base line to the one marked ten is a pe-riod of ten days, and you see that the guinea-pig inadding to i

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