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POPULAR SCIENCE REVIEW. 
■when the pollen of some other species is employed. This is 
another proof, either that the old doctrine, as to species not 
intercrossing, is not wholly true, or else that we must greatly 
extend the limits of what we are pleased to call species. The 
conformation of the flowers throws some light on these pecu- 
liarities, hence it may be advisable in a very general way to refer 
to their structure. 
Beginning -wdth the bracts below the flower, we have only to 
remark that their number is invariably three, and though their 
form varies much in the different species, and often indeed 
affords good means of distinguishing them one from another, 
they do not apparently affect the proceedings within the flower 
itself. Within the bracts is the flower proper, consisting of a 
top- shaped or urn-shaped tube, surmounted by the calyx- lobes 
and (when present) by the petals. Inside these comes a series 
of fringe-like threads in one or more rows, the outermost 
usually distinct from each other, the inner ones often so closely 
united as to form a little sheath or membranous ring, with only 
the tips of the component threads detached. These threads are 
collectively called the corona,” or the crown, and they serve 
to separate the upper part of the calyx from the lower part, 
which has been rightly called the nectary, inasmuch as there, 
and there only, is the honey-like liquid secreted. This nectary 
is really the interior of the urn or top-shaped tube of the calyx, 
to which we have before alluded ; its form varies greatly accord- 
ing to the species, but its function, so far as we have seen, is 
the same in all the species. We shall presently see the use of 
all this apparatus which adds so greatly to the beauty of the 
flowers, and pass on now to the other organs of the flower. 
Standing up in the centre of the nectary and protruding beyond 
it, is the column sometimes called the gynophore, or the 
gynandrophore, because it bears the male and female organs 
This column is girt, near the base, by a broad pulley-shaped 
ring, which, with the inner row of the corona, serves to 
shut off the nectary proper from the other floral organs. 
From near the top of this column the five stamens proceed, each 
bearing an anther, which originally has its inner face pressed up 
against the ovary in the centre of the flower, but which, before 
the pollen is ripe, alters its position so as to turn its face towards 
the outer side of the flower. The purport of this change we shall 
explain by and by. As for the pollen in the anthers, let every 
one in possession of a microscope, and who has not already done 
so, take the first opportunity of examining it. Eichly will he be 
rewarded, for there are few things more beautifully marked than 
these little pollen globes of the Passion flower. Above the 
stamens, perched at the top of the column, is the ovary, sur- 
mounted in its turn by three styles, which with their thickened 
