112 PROF. T. H. HUXLEY ON THE GENTIANS. 
' Perimelite. Mesomelite. 
Most differentiated. Stephananthe. Ptychanthe. 
Lissanthe. 
Keratanthe. Lophanthe. 
Limnanthe. 
. Actinanthe. Asteranthe. 
Least differentiated. SN _ 
Haplanthe. 
(Hypothetical.) 
Or, to put the facts in another way, the several types in each 
series may be regarded as modifications of a common plan, of 
which the simplest exemplification is to be found in Actinanthe 
and Asteranthe respectively. If so, it is an easy step to the con- 
clusion that both these are slightly diverse modifications of a still 
more simple, but, at present, purely hypothetical, common form, 
having the main features of Actinanthe and Asteranthe, but with 
the nectarial surfaces either feebly developed on both ovarian 
and corolline surfaces, or entirely absent. I will call this hypo- 
thetical ** Ur-gentian," Haplanthe. 
Thus far I have endeavoured to travel no hair’s breadth beyond 
matters of observation and their obvious relations. Itis plain that, 
even if all the five hundred and odd species of Gentianew had been 
created separately and raised in pots in the Garden of Eden, their 
morphological relations would have been exactly what they are. 
But, to a believer in evolution, the significance of these facts is un- 
mistakable. With whatever caution one may be inclined to regard 
phylogenic speculations, it is hard, in such a case as this, to resist 
the force of the suggestion, that these morphological relations do 
really indicate the path which the evolution of the plants com- 
posing the Order has followed. At any rate, the evidence is 
strong enough to justify us in accepting this conception as & 
good working hypothesis. And there is the more justification 
for doing so, that, if we regard the morphological facts by the 
light of Sprengel and Darwin's theory of the origin of flowers, 
they at once become intelligible. 
