The Absorption Of Water By Seeds Of Lolium Perenne (L.) AND Certain Other Gramineae

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Summary.

1. The methods used in these investigations into the problems of absorption of water by seeds are described. A modification in the method of direct weighing is suggested.

2. The rôle of the pale in absorption is discussed. The pale exercises a retarding effect on water absorption, so long as it is attached to the caryopsis. But the attachment is broken as the absorption of water with consequent swelling extends from base to apex.

3. The cuticular membranes of the seed retard the absorption of water, but the permeability is increased by the stretching of the cuticle, consequent upon swelling.

4. The earliest absorption takes place through the micropyle. This water can diffuse upwards to a certain extent. At the higher level it causes the endosperm to swell, which in its turn induces greater permeability of the cuticular membranes. The water absorbed at this higher level diffuses upwards to a slight extent, and causes greater permeability at a still higher level. Thus, there is a progressive extension upwards of the area of absorption induced by the slight upward diffusion of water.

The writer wishes to acknowledge his indebtedness to Prof. W. Stiles for help in the preparation of the manuscript of this paper; to Mr F. R. Horne for help in the course of the work; and to Mr R. L. Stevenson for making the diagrams which accompany this paper.

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