Hill. — Studies in Seed Germination. 
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EXPLANATION OF PLATE XX. 
Illustrating A. W. Hill’s paper on Studies in Seed Germination. 
The photographs have kindly been taken by Mr. J. Hutchinson, The Herbarium, Kew. 
All the specimens figured in the plate are Cyclamen persicum. 
Fig. 1. Cyclamen. A young plumular leaf put in as a cutting. A callus has developed, but 
no roots have been formed ; the leaf lived in this condition for about a year. 
Fig. 2. C. A cotyledon — the normally produced first cotyledon — put in as a cutting. Roots 
are quickly developed from the base, and there is no formation of a knob of callous tissue. - 
Fig. 3. C. A cotyledon cutting, showing a further stage of development. A tuberous swelling has 
grown out at the base of the root, and on this a plumular bud has formed which has given rise to 
plumular leaves and shoots ; the lower side of the tuber is rounded and the roots are produced from 
the upper surface. 
Fig. 4. C. A decapitated seedling tuber, showing the development of adventitious leaves from 
the surface of the tuber just below the cut surface. The adventitious leaves behave exactly as do 
the cotyledons. 
Fig. 5. C. Two seedlings, from which the first cotyledon has been removed. The scar, c. 1, can 
be seen. The second cotyledon, c. 2, has developed, and the lamina has been removed. In each case 
new laminae have developed from the adaxial side of the petiole. 
Fig. 6. C. An older tuber decapitated. In this case several plumular leaves had developed before 
the upper half of the tuber was removed. New adventitious plumular buds have been formed from 
the centre of the cut surface of the tuber, and not from just below the margin of the cut as in the 
seedling. The adventitious leaves in the case of these adult tubers behave as do the plumular leaves. 
Fig. 7. C. A decapitated seedling tuber, about a year old, which has developed two plumular 
axes from the margin. The surface of the cut can still be distinguished. 
