. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 56 RUTH STOCKING LYNCH AND HELEN BERENICE SMITH What has been said concerning the inheritance of decreased fecundity is likewise true for longevity. Animals whose length of life has been altered by long cultivation under adverse conditions produce progeny that show a normal longevity when grown in a favorable environment. Depression produced in this rotifer by the action of an inadequate cul- ture medium lasts only as long as the stimulus which produces the de- pression is present. This result differs a little from the resul
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 56 RUTH STOCKING LYNCH AND HELEN BERENICE SMITH What has been said concerning the inheritance of decreased fecundity is likewise true for longevity. Animals whose length of life has been altered by long cultivation under adverse conditions produce progeny that show a normal longevity when grown in a favorable environment. Depression produced in this rotifer by the action of an inadequate cul- ture medium lasts only as long as the stimulus which produces the de- pression is present. This result differs a little from the results of \Yhit-. 4 3- 2 • 1 - 9 10 11 12 13 15 FIG. 11. Experiment II. 1929. Recovery curve based on length of life. Horizontal axis represents successive generations; vertical axis, mean length of life in days. Asterisks indicate generations in which return to 100 per cent me- dium occurred. ney (1912) and Xoyes (1922). who found that the depression produced by the action of alcohol persisted for two generations after removal to a favorable medium. Mechanism of tlic Effect As to the precise way in which the environment operates to produce depression, we have no evidence. 1 1 may be that in a medium deficient in food, the rotifer grows at the expense of its own productivity; that in the ordinary metabolic processes it uses up part or all of the yolk ^tore<l in the vitellarium, making the production of many eggs impossible. thus bringing about a depression in fecundity. This process may be correlated with the length of life of the organism to the extent that when all the stored yolk has been used up in metabolism, the animal has no more reserve on which to depend and consequently dies, thus bringing about a lowering in longevity. Or, on the other hand, in such a weak food medium the animal may use all the food it receives for its own body metabolism and not have enough left to produce yolk for many eggs, causing a reduction in fecundity but not in longevity, the animals. Pleas
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