72 
The Origin of the Perianth in Seed-Plants. 
flowers, shows a further elaboration of the perianth into two distinct 
series, an outer (calyx) for protection, an inner (corolla) for attractive 
purposes. Frequently the inner is more or less reduced to nectar- 
containing structures when the attractive function is performed by 
the calyx. Mr. Worsdell puts forward Celakovsky’s view that the 
petaloid calyx represents a more primitive form than the green 
calyx of other members of the order and of most Dicotyledons. It is 
not easy to correlate this with the view that the earliest flowers 
were wind fertilised, and that a petaloid development occurred later 
as an accompaniment of entomophily. The protective calyx of the 
dichlamydeous flower, seems comparable rather with the simple 
protective perianth of the monochlamydeous flower, while the corolla 
is a later development and in many cases may have arisen by 
modification of stamens. The stamens are often highly attractive 
without showing any structural modification; in Potcnnogeton a 
petal-like structure grows out from the back of each stamen ; 
generally however the sporogenous character becomes lost in the 
conversion of stamen to petal. 
Too much stress should not be laid on the interchangeability of 
function in various Ranunculaceae to which Mr. Worsdell refers. 
Where a floral axis bears bracteoles, sepals, petals, stamens and 
carpels following in a more or less continous spiral, it is not a 
matter for surprise, that, with a number of foliar organs arising thus 
in simple succession on the same axis, there should be an absence 
of definiteness in the limitation of distinct series. 
A. B. Rendle. 
P, Madmcy, Printer, 151, Whitfield Street, Pitzro5 7 Square. 
