Changes in Deoxyribonucleic Acid and Total Nitrogen in Planarian Worms during Starvation

When planarian worms are subject to starvation their volume decreases, and the fact that they can survive even when their volume has been reduced to a small fraction of the original, sometimes to less than 1 per cent., has made these animals the object of several investigations of starvation effects. One question to which special attention has been paid is whether, in the starved animals, it is the number or the size of the individual cells, or both, that have been reduced in correspondence with the reduced volume. The previous results pertaining to this question will be dealt with in the discussion, where it will be shown that quite different answers have been obtained. Recent biochemical investigations of the effects of starvation on various organs and tissues in mammals (cf. the review by Davidson & Leslie, 1950) have demonstrated that the content of deoxyribonucleic acid (DNA) remains completely constant under conditions of starvation, whereas considerable losses occur in weight and other quantities.