Floral Evolution. 83 
(i.) Progressively increasing conspicuousness attained 
either:— 
(a.) By enlargement of the individual flower, or, as 
is by far the more general case, 
(b.) By excessive branching of the floral axes to 
produce aggregation of the flowers into dense 
inflorescences. This branching tendency has 
not impossibly extended itself, in many groups 
of the Archichlamydeae, to the parts of the 
individual flower, thus constituting a Secondary 
Branching tendency, resulting in secondary in¬ 
definiteness in the numbers of the floral parts. 
(ii.) Devices of floral structure or habit which have 
obvious relation to insect-visits ; chief of these, 
and the only one of such general occurrence as 
to be named a tendency, is Zygomorphy. This 
may occur in solitary or loosely aggregated 
flowers, but is illustrated more generally by the 
outer florets of a relatively close inflorescence. 
(Hi)- Fusion of parts, more particularly to form tubes. The 
most important type of fusion is sympetaly, 
which lies at the base of the primary division 
of Dicotyledons. 
4. The “ primitive flower,” or prototype, will be, of course, 
one in which the working of these principles is realized the least. 
There will be no economy in production ; the parts will be, there¬ 
fore, produced in indefinite numbers ; and there will be no great 
specialization for the reception of insect-visitors—no aggregation, 
chorisis, zygomorphy, or fusion of parts. An analogy to such a 
prototype is not wanting in the Gymnospermse, for we find it in 
certain members of the Bennettiteae, and reflected in the typical 
flowers of certain Ranalian orders, e.g., the Magnoliaceae. 
. 1 . . 1 . 
O' O' O' O' 
It is our purpose in the next chapter to illustrate the working 
of these principles, as briefly as possible, in the series Archichla¬ 
mydeae, and by this means to introduce the Sympetalae, within 
which group an attempt will be made to trace the evolutionary 
progression in some detail. 
(to be continued). 
