The phenomenon that discs of various storage tissues increase in weight when in water, has already been investigated by Stiles and J0RGENSEN (1917), who have made an investigation of the swelling of plant-tissues in water; they have worked with discs of potato and carrot. Immediately after being cut, the discs, with a diam. of 1.8 cm and a thickness of 2 mm, are put into water which is not aerated. From time to time the fresh-weight is determined, the swelling being expressed in % increase of the initial fresh weight. They have found that a great deal of water is taken in, especially at the beginning, in the first few hours. They state that changes in the weight of the discs is almost entirely due to the passage of water into or out of the tissue. The weight of the small amounts of dissolved substances which enter or leave the tissue is negligible in comparison with the weight of the water passing. The phenomenon has also been noticed by Steward (1933) and Berry and Steward (1934), who give, in table I, the fresh-weight of various storage-tissues at the beginning and at the end of a period of 91 hours in an aerated solution of 0.75 m.eq. KBR. There is in general an increase in the fresh-weight, the various storage-tissues, however, varying very much in this respect.