and on the Structure of the Seed in the Rhamnacese. 81 



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 I found, on the contrary, that the micro- 

 pyle is placed over the fascicle of stigmatic tissue, evidently in 

 its normal and proper position. Another confirmation of the 

 same view occurs in Rhamnus Alaternus, where, in the ripe seed, 

 the raphe is exactly dorsal, as in R. catharticus : here I found 

 the unimpregnated ovule having its raphe precisely in the same 

 position as in the seed, with its micropyle placed over the im- 

 pregnating point of the placenta, and situated between the funicle 

 and the axis of the ovary, proving that in this case there had 

 been no twisting of the funicle, and consequently no pivoting of 

 the ovule. I have also examined the living ovary of Rhamnus 

 catharticus in an extremely young state, long before the ripen- 

 ing of the anthers, and therefore prior to its impregnation, and 

 1 have found the raphe most distinctly upon the dorsal face, 

 precisely in the same position which it occupies in the ripe seed. 

 All the evidence that I have thus been able to collect tends 

 therefore to subvert Mr. Bennett's hypothesis. On the other 

 hand, the explanation I have offered on a former occasion *, of 

 the cause of a dorsal or lateral raphe occurring, as I believe it 

 does, universally throughout the lihamnacea, appears to me 

 quite satisfactory : here, from a most simple and natural cause, 

 originating either in the epipylar or allopylar pullulation of the 

 nascent development from the basal placenta, we have the ovule 

 either with a dorsal or lateral raphe ; and, where dorsal, it is 

 forced into that averse position by the mere act of the resupina- 

 tion of the ovule owing to the pressure of its growth against the 

 base of the cell, in the manner first sagaciously suggested by 

 Mr. Brown in the case of Euonymus. Had the same epipylar 

 pullulation originated out of a higher point of the axis of the 

 ovary, we should have seen in that case a pendent ovule with a 

 ventral raphe, as occurs in the neighbouring family of the Celas- 

 tracece, where in the same cell, from the cause here assigned, we 

 sometimes meet with ovules, some with a ventral and others 

 with a dorsal raphe. 



* Ann. Nat. Hist. 3 ser. iv. 25. 



