H. F. Wernham. 
116 
in which the anthers are typically sessile about the mouth of a tube 
composed of the united filaments. A staminal tube, again, is a 
familiar feature of the Papilionatae. 
The consideration of tube-formation leads us to make a 
necessary digression from the subject of fusion, to a tube-forming 
tendency among the Archichlamydeae which is far more extensive 
than those already mentioned—namely, by means of the progressive 
hollowing of the floral receptacle. This finds expression in the so- 
called “calycifloral ” arrangement; and this, apart from its relation 
to insect-adaptation in virtue of the consequent formation of a tube, 
reverts in its significance to the primary principle of economy in 
production ; for it permits of the coalescence of carpellary with 
receptacular tissue, and material is obviously economized as the 
result. 
The progressive hollowing of the thalamus is foreshadowed even 
in the Ranales, of which the Calycanthaceae and Monimiacese have 
“ perigynous ” flowers. Perigyny is a critical character of the 
Rosales; and the series of rosaceous types illustrative of the 
progression from hypogyny to extreme perigyny tantamount to 
epigyny, is familiar to all. The Geraniales and Sapindales—the 
“ Disciflorae ” of Bentham and Hooker—have escaped this tendency, 
although the Celastraceae reveal a certain leaning to epigyny by the 
sinking of the carpels in the flattened receptacle. The Thymelaales 
afford an excellent illustration of an intermediate stage in the 
calycifloral process; for here the receptacle is hollowed into a long 
tube, the frequent colouring of which displays its relation to insect 
visits; but the ovary remains free, as a rule, at the base of this 
tube. In Rhamnales a similar arrangement obtains, but the ovary 
is in this case usually united with the receptacular wall. 
The final stage is seen in, e.g., group C of Parietales, in Myrti- 
florae and in Opuntiales, in which the ovary is completely sunk in 
the axis and united with it, i.e., is inferior. Engler’s division of 
his cohort Parietales is instructive in this connection; in group A 
the pistil is free, upon a convex axis; in B, the pistil may be 
situated in a tubular axis, but is rarely united with it; while in C, 
which includes the Begoniacete, the ovary is inferior. 
It will be convenient to suggest at this juncture that inferiority 
of the ovary may, not improbably, have been produced in descent 
in more than the one way we have indicated, although this latter is 
alone in having left any continuous trace among existing plants. 
The point that we wish to urge here is, that, whatever the evolutionary 
