Floral Evolution. 
”3 
cohort every gradation from relatively slight to complete union 
of the carpels may he observed from a comparative study of 
the natural orders and genera. 
A tendency to the unilocular condition of the ovary is seen in 
the series Rosales, Geraniales, Sapindales, Rhamnales, Malvales, 
Parietales (group A), 1 and Myrtiflorae, in which, although the number 
of loculi usually equals the number of carpels, examples of a one- 
chambered ovary occur with greater or less frequency. In the 
remaining groups of Parietales, in Opuntiales, and in Thymelaeales, 
the ovary is prevailingly unilocular. 
In Myrtiflorae and Umbelliflorae, the number of loculi equals 
the number of carpels; so that, in the Archichlamydeae, the tendency 
to economy as expressed by a unilocular and uniovulate ovary is not 
so powerful as to find reflection in its highest groups. We shall 
find in the Sympetalae, however, that this tendency is much more 
clearly defined. 
Progressive reduction in the number of ovules is to be expected, 
in accordance with the principle of economy in production ; but this 
tendency is, we shall find, not so marked as the tendency to 
oligomery of sporophylls. We may suggest that the “effort” to 
produce an ovule is far less than the effort to produce a sporophyll; 
and, in many cases, prodigality in ovule production is counter¬ 
balanced in the course of seed-production, many of the ovules, or 
even all save one, being aborted at a comparatively early stage of 
development. 
In the flowers of group (a) one or two ovules only are present 
as a general rule, the exceptions being found in Salicales, Proteales, 
Aristolochiales, and some Centrospermae, in which groups the ovary 
is multiovulate. 
Of group ( b ) Rhaeadales, Sarraceniales, Rosales, Malvales, 
Parietales, Opuntiales, Myrtiflorae, usually have an indefinite 
number of ovules in the ovary; while 2 or 1 (per loculus) is the 
usual number of ovules in Geraniales, Sapindales, Rhamnales, and 
Thymelaeales. These latter are the groups, it is pointed out, in 
which no general tendency to secondary branching has been noticed. 
In Umbelliflorae the climax of economy is reached in the 
invariable production of one ovule only for each carpel. 
We gather from the foregoing summary of the Archichlamydeae 
1 Includes principally the Guttiferales of Bentham and Hooker. 
