2 l8 
H. F. Wernham. 
already among the Pentacyclidae. Zygomorphy, we shall observe, 
is followed by oligomery of the androecium, undoubtedly with 
relation to the entry of the insect-visitor into the flower. Aggre¬ 
gation of florets is followed by reduction of the calyx, usually to a 
pappus ; the protective function in the capitulum is discharged by 
the mutual protection afforded by the closely aggregated florets, 
and also by the common involucre ; the calyx is thus available and 
utilized for another function, viz., that of fruit-dispersal. 
Economy in production of megasporangia, we have seen, 1 is 
not an extensive tendency among Archichlamydeae; it seems, 
however, to constitute a marked feature of the Tetracyclidae, the 
ovary in the highest forms—comprising nearly 30% of the total 
number of species—being uniovulate, with one fertile loculus only 
(Asterales of Bentham and Hooker). A single ovule in each loculus 
of a hi- or multi-locular ovary characterizes some Contortse, a large 
section of Tubiflorae, and many Rubiales. 
C ONTO RITE. 
The natural orders of this group, together with those comprised 
under Engler’s Tubiflorae, have been designated Bicarpellatce by 
Bentham and Hooker, in virtue of the fact that, with very rare 
exceptions, the ovary is in all cases bicarpellary. A similar 
condition obtains in the most advanced members both of Archi¬ 
chlamydeae (Umbelliferae) and of Sympetalae (Composite), so that 
fully three-quarters of the species in the latter series have a bi¬ 
carpellary gynaecium. We are led to the conclusion that this 
condition represents the highest expression of the economy 
principle in so far as the gynaecium is concerned ; and it is found 
very generally, we should mention, even where the ovary is uni¬ 
locular and uniovulate. In the Bicarpellatae, however, the uni¬ 
locular ovary is a decided exception. 
The cohort Contortae of Engler is coincident with the Gentia- 
nales of Bentham and Hooker, and includes the natural orders 
Oleaceae, Salvadoraceae, Loganiaceae, Gentianaceae, Apocynaceae, 
and Asclepiadaceae; these Orders are identical in name and 
composition in the two systems. Their typical essential characters 
are displayed in the annexed table. 
With the curious exception of the Oleaceae, the stamens are 
invariably isomerous and alternate with the corolla-segments in this 
cohort; in the Oleaceae economy has proceeded to the degree of an 
androecium of two stamens only. 
1 Supra, p. 113, 
