System of the Female ‘ Flozvers ’ of Conifer ae. 535 
there appears to be no sufficient evidence for such a former 
state of things, the bundle-system in these plants arising as 
a single unit from the central cylinder of the axis, and 
seemingly supplying a single appendicular organ. In A. Bid- 
willii , Hook., however, there is undoubted evidence forth- 
coming, for in this plant, as we have seen, there are two 
distinct sets of vascular strands arising at separated points in 
the central cylinder of the axis, one of which exhibits inverted 
orientation of its parts. This, assuredly, would not be likely 
to happen if the appendicular organ which they supply 
represented a single scale. Any anatomist would say that 
the uppermost of these two systems of bundles belonged to 
some organ axillary to the bract which the lower bundle- 
system supplied. This I hold to be the case, the axis of the 
axillary bud being suppressed, and the latter reduced to 
a single leaflet, representing the vegetative outer integument 
of the sporangium, the cylinder of bundles which originally 
supplied this now obsolete axis has also become reduced to 
an arc of bundles such as commonly constitutes the bundle- 
system of a leaf. And Van Tieghem is thus far right in the 
views he put forward. In all species of Araucaria, however, 
the two bundle-systems become, either in the cortex of the 
axis or subsequently in the stalk of the appendage, more or 
less intermixed, as we have seen. In the majority of species 
the two systems appear to exist as a unit at their first origin 
from the central cylinder . This state of things seems to 
indicate an adaptive modification of the structure of long 
standing. 
As regards the structure of the ventral portion of the 
appendage, the occurrence of concentric bundles seems to 
show that Araucaria is an ancient type of plant, and 
approaches the Cycads in this respect, for in the sporophylls 
of these latter concentric bundles are very frequent. The 
structure of the bundles in the free ligular portion of the 
appendage clearly proves that this organ is of foliar nature, 
and refutes the opinion of Strasburger that it represents the 
terminal portion of the axillary axial organ. 
