Mr. J. Miers on the Affinities of the Olacaceae. 183 



before quoted, of the growing together of several embryos ; for 

 he asserts, that several embryonary sacs are contained in a single 

 ovule, and are fertilized, but it rarely happens that more than 

 one of these arrives at perfect development*, and he therefore 

 concludes, that the doubling or trebling of the radicular end of 

 the embryo of Viscum cannot be owing to the cohesion of several 

 embryos. It appears to me that many of the changes that 

 really take place in such cases have not yet been observed, and 

 that we have still much to learn concerning the true nature of 

 such developments : this is a subject of deep interest, worthy of 

 the most attentive examination. I have mentioned that in the 

 Olacacece, as well as the Santalacece, although the cionosperm 

 sometimes exceeds the limits of the ovules, the free apices of the 

 three ovular bodies are more frequently seen to extend above 

 the top of the column. M. Decaisne describes the ovules in 

 Viscum album to be several and erect, that one of these becomes 

 fertile, while the two others are abortive and appear like filaments 

 at its base. It is probable that the cionosperm is here very short, 

 and that the free apices of the ovules have been mistaken for the 

 ovules themselves; it may be also that the free apices of the 

 probably yet un impregnated ovules, distinguishable in the ova- 

 rium of the Olacacece, Santalacece, &c, may be nothing more than 

 the exserted portions of the embryonary sacs, so ably described 

 by Mr. Griffith : these are points very difficult of determination 

 in dried plants especially, where the parts are so extremely minute 

 and delicate. In Opilia, and again in Champereia, the three 

 suspended ovules, at the period of the fall of the flower, appear 

 closely aggregated upon their columnar support, and from their 

 extreme minuteness, they are easily mistaken for a single erect, 

 stipitate ovule ; but I have found, by alternately moistening and 

 allowing them to dry, that air intervenes between the delicate 

 membranes, and renders them clearly distinct. I have already 

 alluded to the fact, but as yet we know nothing of the cause, of 

 the non-production in all the Cionospermce, as well as in Viscum, 

 of the usual coverings that in ordinary cases are generated over 

 the pristine ovule. We must not lose sight of the important 

 circumstance, observed by M. Decaisne, that in Viscum album 

 the embryo is not developed till a long period after the fall of 

 the anthers f, nor of those of Mr. Griffith J, equally showing, 

 that both in the Indian species of Viscum and Loranthus, the 

 ovulum is a formation, subsequent to the act of impregnation ; 

 " a remarkable and unparalleled fact, that tends to increase the 

 difficulty of understanding, or even conjecturing, the nature of 



* Ann. Nat. Hist. Ser. 1. vii. p. 171. 



t Sur le developpement du Pollen du Guy, &c, Mem. Acad. Roy. 

 Bruxelles, vol. xii. 

 % Linn. Trans, vol. xviii. p. 77> 



