56 
REPORT ON BOTANY, MDCCCXLI : 
a folium lohatum, or stipulatwn, or eyen compositum, is pro- 
duced. If one of the two lateral bundles is separated earlier 
than the other, and earlier than the principal nerves, then the 
side of the leaf, where this happens, is always more developed 
than the others. If the curvature, which measures the dis- 
tance of the central nerves to the side nerves, at that point 
of the branch where the bundles separate from the wood, is 
very large, then the leaf is generally lobed and stipulate. 
The epilogue of Mirbel is singular. The labour, he says, 
was obliged to be done, it was necessary for science ; it is 
well that it has been done with diligence. Good fortune has 
frequently a greater share in making important discoveries in 
the experimental sciences than cleverness. The phytologist, 
who has recourse to anatomy, can derive no more from the 
object than there is in it, however industrious he may be. 
M. Payen is not wanting in capability, he only wants the op- 
portunity. Mirbel wished to say. What is the use of accuracy 
in research, if the variety discovered is not brought into 
combination with the whole ? They are preparatory labours 
for the fortunate man who discovers their combination. 
The Leaves of the Coniferce appeared to me so remarkable, 
that I subjected them to an examination ; the description of 
which is to be found in the Icon. Select. Anat. Bot. part ii. 
tab. 5, (1840.) They are principally distinguished by only 
having an ordinary simple (sometimes, however, perhaps a 
double) vascular bundle, which runs longitudinally through the 
leaf, without producing branches or ramifications. The Folium 
acerosum might be thus characterized. They generally also 
have one or two resinous channels, which run through the 
whole leaf ; the leaves of Abies balsamea have them at the 
sides (fig. 9) ; the leaves of Thuja occidentalis and Juniperus 
communis (figs. 11 and 12), have only one resinous channel 
near to the principal nerves. Many have a double upper 
layer, as, for instance, Abies balsamea (fig. 9, e e), and Juni- 
perus sabina (fig. 10, c c) : the cells of some of them are also 
lengthened laterally, beneath the upper layer, as, for instance, 
on the upper surface of the leaves of Abies balsamea (fig. 9, 
€ c). The form of the leaves of Thuja occidentalis is strange, 
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