Natural Family of Plants called Conifere. 175 
concrete, and by a comparison with the proper leaves, I think there can remain 
no doubt of their origin. The apex of the supposed concrete bracte is free, 
and in the mature cone overlaps the summit of the placentary region, which 
is situated on the inner surface of the scale, near its apex, and which at that 
period is found greatly enlarged. The rapid enlargement of the placentary 
region prevents the ovula, which are always situated on its under side, from 
assuming an erect position, and they are consequently obliged to take a 
downward direction; but in no case do they form any lateral adhesion with 
their axis, and there is consequently no raphe, and the foramen and point of 
attachment retain their original position ; the ovula are, therefore, atropous ; 
and the circumstance of the foramen occupying the lower extremity of the 
seed, arises from the ovula being forced to take a downward direction by 
the overhanging placenta. 'The hilum or point of attachment appears to be 
placed a little obliquely on the inner base of the seed from the extension of 
the winged border beyond it, which in this case consists of the cuticle merely 
and not of the entire substance of the testa. "The testa in Coniferæ consists 
of a single integument only, the secondine of Mirbel, as Mr. Brown pointed 
out many years ago; and what I described as a second integument in Pinus 
bracteata and other species of the group of Silver Firs, is merely the cuticle of 
the nucleus, which in all these species is very conspicuous, and similarly 
winged like the proper testa, which by its open apex exhibits an analogy to 
the testa or cupula of Tazus. 
The cotyledons in most Conifere are verticillate, and we therefore con- 
stantly observe a tendency to assume the same arrangement in the after 
leaves and other organs derived from them; but from the elongation and 
unequal development of the axis, the verticillate disposition is departed 
from, and they most frequently exhibit a spiral arrangement. A multitude 
of such spires in close contact, as happens in the branches of Araucaria and 
in the cones of Pinus, would of course give an indefinite appearance to the 
series ; but in no case does the number of leaves in such a verticil exceed ten. 
In Cupressus the cotyledons are two and opposite, and we constantly find the 
after leaves opposite, the pairs crossing each other give to the leaves the 
appearance of being arranged in four rows. In Callitris the leaves are ar- 
ranged in fours, as in C. quadrivalvis and octovalvis, and the pericarpial leaves 
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