the Structure of the Seed in the Rhamnacese. 77 



was there placed in his order Rhamni, a heterogeneous group 

 composed of Rhamnacea, Celastracece, Aquifoliacece, Bruniacea, 

 Staphylacca, and some other genera. From this association 

 Mr. Brown (in 1814) separated the Celastracece, including the 

 Aquifoliacea, and (in 1818) the Brumacea-, and thus circum- 

 scribed, DeCandolle (in 1825) published an enumeration of the 

 order, wherein Colletia appears as the only genus belonging to 

 the tribe since constituted. We owe to Brongniart (in 1826) 

 the best monograph of the family that has yet been published, 

 where its affinities are well discussed, and where ample charac- 

 ters of the genera are given : here he first separated Retanilla 

 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. End- 

 licher, in the same year, however, adopted the arrangement of 

 Reissek, and accordingly, in his ' Genera Plantarum/ divided 

 the family into six tribes, the Colletiea being one of them, which 

 there comprehends six genera. 



Before I proceed to arrange my own observations, I will offer 

 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 Colletiece. that have come under my scrutiny ; they 

 are constant in the Gouaniete, 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 Colletie^s present 

 the same features ; and as there are many curious circumstances 



