Rub i ales. 
225 
in proportion to the number of such exceptn. This number, however, 
barely exceeds a score ; but the parallel genera referred to present 
a serious problem which calls for careful investigation. In a few 
very rare cases the difficulty has been successfully met—notably in 
the case of Cephalanthus, which, in spite of its uniovulate ovary- 
chambers, is included in the tribe Nancies of Cinchonoideae; and 
this doubtless because of the very characteristic globose capitula of 
Cephalanthus and all the other Naucleas. In other cases the 
affinities, though they may prove clear enough on a closer investi¬ 
gation, are not so obvious ; and this has very probably resulted in 
the wide separation of species which should properly be included in 
the same genus. 
The reduction in ovule-number, we have already stated, is not 
accompanied by secondary septation as in the case of the schizocarpic 
tendency in the Diovulatae section of Tubiflorae {supra, p. 230). 
Nor is there any general tendency to specialization of the fruit or 
seed ; but in some rare instances one of the persistent calyx-lobes 
becomes foliaceous as the fruit develops {Alberta, Neinatostylis, etc.) 
and so aids undoubtedly in its distribution. In several of the 
Cinchonoidese the fruit is capsular and the seeds winged. 
We have seen how varied are the Rubiaceae in their essential 
characters, and the question arises whether the family as arranged 
at present should not properly be divided into « number of families. 
For the most part, however, the series of forms concerned display 
the several characters in so continuous a progression that satisfactory 
critical dividing-lines cannot be drawn ; this difficulty has just been 
illustrated in connection with the character of ovule-number, and 
the same applies to other features, such as carpel-number, inflores¬ 
cence-character, etc. This state of things is in keeping with the 
relative primitiveness of the group, which may be regarded as the 
expression of extensive evolutionary activity, the reflection of 
tendencies at work. 
In the case of at least two tribes, however, Nauclese and 
Galieae, 1 the distinction seems to be sufficiently constant and well- 
defined to warrant their promotion to family-rank. Either tribe 
can be diagnosed in practice at a glance, the first by the perfectly 
spherical compact capitulate inflorescences, the second by its 
familiar vegetative features. There are no forms among other 
rubiaceous tribes which might be regarded as transitional in the 
direction of the Naucleze; and their tribal characters as formulated 
in either of our modern systems of classification may well be 
accepted as the characters of a family, Naucleaceae. 
1 Stellatae Ray, Synops. 223 (1690). 
