Hill. — Studies in Seed Germination. 
425 
there was no production of adventitious roots from the base of the petiole 
as with the cotyledon. The base of the petiole, however, enlarged con- 
siderably and formed a kind of tuber or callosity, but, though shaving of 
the surface of this callosity and other devices to induce root formation have 
been tried, the results have only been negative. The leaf cutting may 
remain alive for a considerable time and increase in size, but it will eventually 
Text-fig. 9. C. persicum. A first cotyledon cutting more fully developed (cf. PI. XX, Figs. 2, 3;, 
showing the cotyledon, c and plumular leaves,//. 1 and 2. The adventitious tuber shows two growing- 
points, gp 1, gp 2. The root is developed from the upper surface or, more correctly, the tube is 
developed below the root, and is more clearly seen in the back view, 9 a. 
die without having formed either root or shoot. One exception to this 
statement, however, must be recorded, as in one case only a young plumular 
leaf from a young seedling did develop a root from the base of the petiole, 
and the leaf cutting, which developed a strong laterally placed root, 
remained alive until February, 1920 ; there was, however, no development 
of an adventitious bud (PL XX, Fig. 1, and Text-fig. 10). 
A section through the callosity or swollen base of the petiole reveals 
several cortical ‘nests’ of lignified cells — and a few such ‘ nests ’ are also 
