232 
CONTRIBUTIONS TO BOTANY. 
from Colletia, and at that time he was able to muster only seven 
species in these two genera. Subsequently to that period, the 
number of plants belonging to the Rhamnacece have become 
greatly multiplied, and the characters of the species better 
known •, several new genera have been established, but no regular 
enumeration has appeared since that of Brongniart above men- 
tioned, so that a proper monograph of the order has become a 
great desideratum. It seems that Reissek (in 1840) was engaged 
in this important task ; but his promised monograph, after a 
lapse of twenty years, has not yet made its appearance. Eud- 
licher, in the same year, however, adopted the arrangement of 
Reissek, and accordingly, in his ‘ Genera Plantarum,^ divided 
the family into six tribes, the Colletiece being one of them, which 
there comprehends six genera. 
Before I proceed to arrange my own observations, I will ofier 
a few prefatory remarks upon many points of structure that I 
have met with in this family, and which do not appear to have 
been noticed. These developments I have found in all the 
species of the ColletiecB that have come under my scrutiny ; they 
are constant in the Gouaniea, and have been observed in many 
genera of the Rhamnea \ but I have not attempted a general 
examination of the whole order, as this required more time 
than could be devoted to it, and would have drawn my atten- 
tion from Other investigations in which I have been long 
engaged. 
The fruit in all the genera of the Colletiea is polycarpous, the 
normal number of its cells being three, rarely four : these are 
sometimes reduced to two, even in the ovary ; and if the fruit be ^ 
occasionally monospermous, as often occurs in Trevoa, Colletia, 
&c., the vestige of each abortive cell is always distinctly visible. 
The ovules are invariably solitary in each carpel, always erect, 
and fixed in the bottom of each. cell ; the radicle of the embryo 
constantly points to the hilum. 
The seeds throughout the whole tribe of the Colletiece present 
the same features 5 and as there are many curious circumstances 
connected with their structure, those of Colletia dumosa, collected 
by me in Chile thirty-five years ago, are selected as an exam- 
ple. They are of an oval form, about line long, 1 line in 
diameter, sometimes slightly compressed, often with an obsolete 
ridge on the ventral face, which has been mistaken for a raphe ; 
erect ; with a very hard polished outer surface, appearing finely 
granulated when magnified : this outer coating is corneous in 
texture, becoming softer by long maceration, when it may be 
cut through with a sharp knife ; it is somewhat translucent, but 
rendered densely black by the lining that adheres to it ; at its 
base, in a transverse direction in regard to the fruit, is seen a 
