1. Under all the intensities of starvation investigated, the longevity of the imago stage of Drosophila was as a rule diminished. At the same time, flies which were starved for six hours out of every 24 and which were not deprived of water, lived at least as long as the controls.
2. The longevity of flies increased in inverse proportion to the intensity of starvation.
3. The longevity was greater in series in which the flies were never subjected to lack of water than in those in which intermittent starvation without water was practised.
4. The injurious influence of longer, though less frequent fasting intervals was more pronounced than that of shorter though more frequent periods of inanition, both with or without administration of water.
5. Starvation for six successive hours out of every 24 without water affected the flies most during the middle period of their life. The same effect was found during starvation for 12 successive hours out of every 24 when the flies were supplied with water.
6. With lapse of time the flies became less resistant to the temporary absence of food.
Though the experiments performed did not give any clear results as to the supposed prolongation of life under the influence of intermittent starvation, some valuable hints for further study may be obtained from the observations recorded. The experiments on the influence of starvation for six hours out of every 24 with administration of drinking water must be repeated on a larger scale and it is intended to perform further experiments using a less intense degree of inanition. As with lapse of time the animals become less resistant to starvation, special experiments are also planned in which the flies will be intermittently starved until middle age and thereafter will be fed continuously.