IN THE CLUSIACE^, MAGNOLIACE^, ETC. 87 



view of the question is one which certainly ought to have its due importance, and is one 

 which I have never doubted in the smallest degree, viz. that Dr. Gray has watched the 

 progress of the growth of the seed from the oAOile and could never detect any subsequent 

 or extraneous production over the primine. In the fullest credence of tliis assertion I 

 still think we have convincing proof that such extraneous growth, though he failed in 

 distinguishing it, must have taken place imperceptiltly, in the same way that other 

 observers have witnessed a similar gradual extension over the primine. 



The foregoing discussion has induced me to offer a few additional observations on the 

 nature of the raphe. I have been led into this inquiry by the pha;nomena that present 

 themselves in the Chtslaccw, where I found it cUfficult to assign a reason, why the raphe 

 should in one case consist of a single cord of vessels, almost in a free state, vrithin the 

 inner peUicle of the external arilliform coating, and wholly free from the testa, as inva- 

 riably occurs in the Glusiecc, while in the Tocomitece, the raphe has no connexion with 

 the enveloping aril, but appears imbedded in the slender chartaceous testa, not as in the 

 former case like a simple cord, hut spread in the form of several branching nervures con- 

 tinually subdividing themselves, and distributed in new ramifications throughout the 

 whole area of the testa. There appears here a difference of structure somewhat inexpli- 

 cable, but after a little consideration, we may trace to one uniform rule the varying 

 appearances of the raphe under these different forms and position. We owe to the pro- 

 found investigations of oiu' great countryman Mr. Brown, most of the knowledge we 

 possess regarding the growth and development of the ovule and its original tunics, the 

 changes they undergo diu-ing and after the anatropal metamorphosis, the gradual trans- 

 formation of these tunics into the different coatings of the seed, and the share they afford 

 in the nourishment and development of the growing embryo : but the phsenomena 

 attendant on the formation of the raphe, the modifications which these nourishing vessels 

 undergo, and the different modes of theii- distribution, appear to have excited httle notice, 

 for we find few observations on the subject in the works of physiological botanists. On 

 this account I wiU ventui-e to offer some remarks that have occurred to me in my pend- 

 ing investigation of the Clusiacece. 



Let us now examine some of the circumstances attendant on the inversion of the ovule. 

 Prior to this action, the body of the ovule or nucleus is generally seated within two cups, 

 to wliich the names of primine and secundine are given : these cups gradually increase in 

 size, and grow into complete tunics which envelope and conceal the nucleus, also called 

 the tercine : during this early stage, the vessels destined to noiuish the ovule pass imme- 

 diately from the placenta into the gangylode or common point which unites the nucleus 

 with the secundine and primine then in contact with the placenta ; but dm-ing the pro- 

 gress of inversion, the gangylode, as before shown, becomes removed to some cUstance, 

 and a portion of the placenta is drawn away with it and extended over one side of the 

 primine, at first in the form of an elongated sheath or band, as figured by Dr. A. Gray, 

 carrying with it the spiral vessels proceeding from the placenta and terminating in the 

 now remote gangylode : this placentaiy extension, whatever form it may assume in its 

 subsequent growth, must always remain outside the primine notwithstanding that it may 

 become agglutinated to it. Now these nourishing vessels may be all compacted in a 



