CONTRIBUTIONS TO BOTANY. 
235 
situated, for it is everted yet further from the position mentioned 
in Colletia ; it is seen upon the dorsal face of the seed, — a well- 
known occurrence, that has been ingeniously accounted for by 
Mr. Bennett*; but before we adopt his conclusion, it is desira- 
ble to investigate the circumstances attendant on the phjeno- 
menon. Mr. Bennett says that he has universally found, through- 
out all Rhamnacea, that the ovules, in their early state, uniformly 
exhibit a ventral raphe; and hence he infers that any variation 
subsequently observed in its relative position, whether it be 
shifted to one side or round to the dorsal face, must be due to 
a simple twisting of the funicle, by which the ovule is turned 
upon its axis, either to the extent of a quarter or of half a 
revolution. Were this explanation required only in the case of 
the raphe becoming dorsal, we could scarcely refuse our assent 
to it, because in that case it appears to solve the difficulty with 
apparent satisfaction, notwithstanding that Mr. Bennett con- 
fesses his inability to assign any cause for so singular a rotation 
of the ovide. 
The first point to be considered is the soundness of the foun- 
dation of the argument, that at the period of its fertilization the 
ovule has its raphe directed to the ventral side, and that it sub- 
sequently turns away from it by a lateral torsion of its funicle. 
Mr. Bennett states [he. cit. p. 131) that he has invariably found 
this to be the case in the Rhamnacea ; and this statement has 
been accepted as an indisputable fact by nearly all botanists. 
Some few, however, have ventured to cast a doubt on the sub- 
ject ; Mr. Clarkef says he has always found the raphe dorsal or 
lateral in that family from an early period ; while Prof. Agardh 
affirms the reality of this latter circumstance, and protests in 
positive terms against the prevalent belief on this subject J ; in 
his work above referred to, he gives a figure as an example of 
the structure (plate 15. fig. 5) where the raphe is turned away 
from the axis of the ovary prior to its impregnation. My own 
observations upon this point, though limited, certainly favour 
the latter view ; for I have found, in repeated examples of 
Rhamnus chlorophorus where the raphe in the ripe seed is half 
lateral, half dorsal, that, in its unimpregnated ovule, it occupies 
exactly the same position ; had there been any previous pivoting 
round upon its funicle in this case, the micropyle would have 
been turned away from the point necessary to its fertilization, 
and the funicle would consequently have intervened between the 
foramen of the ovule and the impregnating point protruding 
from the placenta ; but 1 found, on the contrary, that the micro- 
* Plant. Jav. rar. 131. 
t Linn. Proceed, ii. 148-150; Ann. Nat. Hist. ser. 2. xi. p. 85. 
+ Theor. Syst. Plant, p. 178, and plate 15. fig. 5. 
2 H 2 
