HETEROTAXY. i 
supply of nutriment, and other means all based on the 
same principle. Some of the Cape bulbs (Cyrtanthus) 
are known not to produce their flowers till their leaves 
have received, In some manner, a check. Fires which 
often destroy the herbage thus have the effect of throw- 
ing the plant into bloom. <A very remarkable instance 
is recorded of the production of flower-buds after an 
injury to the leaf-buds in the ‘ Bulletin of the Botanical 
Society of France,’ vol. ix, p. 146. It appears that 
during the war of the French against the Arabs in 
Algiers, the latter planted several hundreds of Agaves 
with a view to obstruct the passage of the French 
cavalry. The soldiers hacked these plants with their 
sabres, and cut out the central tuft of leaves, or the 
heart, as gardeners call it. The following season 
almost every one of these Agaves sent up their large 
handsome flower-spikes. It is well known that, under 
ordinary circumstances, these plants do not flower 
except at long intervals of time. 
Presence of flowers on spines—'hat the spine, as a con- 
tracted branch, should occasionally produce fiowers is 
not to be wondered at, though the occurrence is by no 
means common. M. Baillon showed at a meeting of 
the Botanical Society of France (‘ Bulletin,’ vol. v, 1858, 
p- 316) a branched spine of Gleditschia bearing a flower 
at the end of each of the subdivisions. This was, 
therefore, strictly analogous with those cases in which 
the peduncle is normally spiney. 
Formation of flower-bud on the petals— An instance of this, 
it is believed, the only one on record, is cited in the 
‘Gardeners’ Chronicle’ for 1865, p. 769, by the Rev. 
M. J. Berkeley, who describes the formation of 
flower-bud on the surface of a petal of Clarkia elegans. 
Reasoning from analogy there seems no reason why 
buds should not be formed on the petals as well as on 
the leaves. 
12 
