Hill . — Si tidies in Seed Germination. 
423 
developed from the top of the decapitated petiole. Similarly, if one of 
the new lateral laminae be removed from its petiole, this secondary petiole 
is capable of producing a new lamina in the same way as does the main 
petiole of the cotyledon. 
I have also been able to confirm Goebel’s experiments with the hypocotyl 
of the Cyclamen seedling ; 1 for if the top of the tuber with its plumule be 
removed, a series of adventitious leaves with petioles are formed round the 
periphery of the mutilated tuber from the cut surface (PI. XX, Figs. 4 and 7, 
and Text-Fig. 8). The new leaves, in the cases which have 
been observed, arise with their outer or lower surfaces 
directed towards the centre of the tuber, and not, as figured 
by Goebel, with their inner or upper surfaces facing inwards. 
As they develop, however, they sometimes change their 
position and face the centre of the tuber. The decapitated 
upper portion of the tuber bearing the plumule will also 
send out adventitious roots from the cut surface — i.e. the 
lower surface — and behave as a true cutting. 
The power of regeneration displayed by the hypo- 
cotyl is well known in some other plants, as for instance 
Anagallis coerulea and Linaria cymbalaria, in which, if 
the cotyledons and plumule be removed, new buds are 
formed freely on the hypocotyl. 2 A similar development 
of hypocotyledonary shoots also occurs in Linuin usita- 
tissimum , Linaria bipartita , and Antirrhinum majus on 
decapitation of the seedlings. 3 
The hypocotyl of Cyclamen appears to differ at first 
from the cases just mentioned, since for about a year 
laminae only are produced from the edge of the cut 
surface, and there are no signs of the formation of new 
growing-points from the tissues of the decapitated tubers. 
In the case of older tubers, as Goebel points out, adventitious shoots will 
also arise when the tubers are decapitated, but the new laminae and growing- 
points arise from the actual cut surface near the centre of the tuber instead 
of from the margin (PI. XX, Fig. 6). 
A further example of limited meristematic activity is shown by the 
cotyledon itself when that organ with its petiole is severed from the 
hypocotyl and treated as a ‘ cutting’ (PI. XX, Fig. 2). 
In the course of a few days, under suitable conditions, roots are freely 
1 Goebel : 1 . c., 1902, pp. 482-4, Figs. 14, 15 ; and 1 . c., 1908, p. 204, Fig. 106. 
2 Kiister : Beobachtungen iiber RegenerationserScheinungen an Pflanzen. Bot. Centralbl. Beihefte, 
xiv, 1903, p. 316. 
3 Burns and Hedden : Conditions influencing Regeneration of Hypocotyl. Bot. Centralbl. 
Beihefte, xix, 1906, p. 383. 
Text-fig. 8. A 
seedling of C.persi- 
cum from which the 
top of the tuberous 
hypocotyl with the 
cotyledon has been 
removed. Adventi- 
tious leaves arise from 
the tuber just below 
the cut surface. The 
specimen shows four 
rudimentary and the 
backs of two fully 
developed leaves. 
