424 
Hill . — Studies in Seed Germination. 
produced from the base of the petiole and grow vigorously, being supplied 
with carbohydrates by the green lamina. 
These leaf-cuttings will live for months, both lamina and stalk increas- 
ing considerably in size, but though numerous experiments were made at 
various seasons, it appeared that the tissues had no power to develop 
a growing-point and in due course the rooted leaf died. 
A series of Cyclamen cotyledons were, however, put in as cuttings in 
October, 1918, in order to see whether any further stages in development 
would take place, and somewhat unexpected results were obtained. The 
petioles produced roots from the base readily as before, and in the following 
February (1919) a second leaf was found to be developing. On examina- 
tion it was seen that a small tuber had formed at the base of the petiole as 
a lateral outgrowth, and it was from this tuber that the second leaf, which 
was plumular in character, had arisen. Nearly all the leaf cuttings put in 
at this time behaved in this manner (PI. XX, Fig. 3, and Text-Figs. 9, 9 a). 
The tuber increased in size and produced roots from near the upper 
surface by the side of the cotyledonary petiole. Roots were not produced 
from the lower surface of the tuber, so that the corm was considerably 
different in character from the corm of a normal seedling, being smooth and 
rounded below and having a tuft of roots on one side only, close to the 
developing plumule. 
The young plants developed adventitiously from the cotyledon have 
continued to grow and produced a plumule with several leaves and flowers 
(March, 1920). 1 
So far the regenerative capacity of the first cotyledon only has been 
referred to ; it is of interest, therefore, to examine the behaviour of the 
plumular leaves under exactly similar conditions of treatment. 
If the lamina of the first, or of any subsequent, plumular leaf be 
removed, no new lamina is developed from the petiole, and in the course of 
a few days the petiole withers and dies. 
Further, such plumular leaves with their petioles were treated as 
‘cuttings’, as described for the cotyledons, but after repeated experiments 
1 The behaviour of the leaves of the ivy-leaved Pelargonium when treated as cuttings was brought 
to the notice of the Scientific Committee of the Royal Horticultural Society, so Mr. Chittenden 
informs me, by Mr. Houston on October 15, 1901. As is the case with the cotyledon of Cyclamen , 
roots were freely produced from the petiole, but no buds developed. I have found, however, in the 
case of leaf cuttingj of Tricuspidaria lanceolata that both roots and a shoot are produced from the 
base of the petiole. Ivy leaves put in as cuttings will produce leaves but no shoots, and have lived 
in this condition for five years, and leaves of Hoya in like manner for seven years (Carriere- 
Jardinier, Multiplicateur, s. 218). De Vries (Prings. Jahrb., xxii, 1891, pp. 68-70) refers to similar 
rooted leaf cuttings of Aucnba , Enonymus japonicus , Ficus elastica , and Camellia japonic a , which 
appear to be incapable of developing adventitious buds and forming plants from leaf cuttings. He 
quotes from Mer (Bull. Soc. Bot. France, xxvi, p. 26), who refers to the case of the ivy-leaf cuttings. 
In the Gardeners’ Chronicle, Feb. 15, 1845, p. 101, D. Beaton refers to the formation of 
‘ callosities ’ on the petioles of leaves treated as cuttings, and to the formation of buds, in some cases ; 
in others, as Camellia , the leaves lived for four years without the formation of buds, 
