L AS AT ORT 
102 PROF. T. H. HUXLEY ON THE GENTIANS. 
observations I venture to offer. But, at present, it is needful for 
me to turn my attention to other things; and if I venture to 
bring forward so imperfect a piece of work, it is in the hope that 
it may be taken up and finished by more competent hands. 
Every botanist is aware that the Gentianeæ constitute one of 
the most natural and well-defined of the Orders of plants. The 
type of structure which runs through the five or six hundred 
species included in the Order undergoes but few and, for the most 
part, inconsiderable modifications. There are no trees and but 
few shrubs among them; a few are climbers ; and there are a few 
saprophytes. The opposition, entirety, and palmati-venation of 
the leaves have but few exceptions; and it is very rarely thatthe 
flower departs from typical regularity. The chief distinctive 
characters of the groups into which the Order is at present divided 
lie in the flower, and indeed in the corolla; since the form and 
proportion of the calyx, the occasional synanthery, and the 
greater or less intrusion of the placent® are characters which 
vary greatly from genus to genus. 
Under these circumstances, I have confined myself almost en- 
tirely to the study of the structure of the flower. I find that 
some seven or eight modifications of that structure are distin- 
guishable; and that these again fall into two series, each of 
which is characterized by a peculiar disposition of the nectarial 
organs, and presents a gradation of forms of the corolla from the 
rotate, or rather stellate, condition, through the campanulate to 
the extreme infundibulate character. 
In one of these series the nectarial cells are situated on 
the inner surface of the cup, from the edge of which the lobes of 
the corolla proceed, and towards its basal end. They are aggre- 
gated in such a manner as to form either a single patch, bisected 
by the vein which becomes the median vein of a corolla-lobe; or 
two patches, one on each side of that vein. I term the Gentiane® 
of this series Perimelite. 
In the other series there are no such patches of secreting-cells 
visible on the corolla; but in many members of the series there 
is a zone of such cells, which encircles the base of the ovary, and 
is therefore furnished by the outer faces of the carpellary phyl- 
lomes, which are often raised into tubercles. -In others, I have 
not been able to make sure of the existence of nectarial cells, 
either on the surface of the ovary or on the stemono-carpellary 
internode, which forms the actual bottom of the flower-cup. But 
