76 PROFESSOR HENFREY ON THE DEVELOPMENT OF THE OVULE 



it appears to me can be urged in favour of the idea that the central body is not a placenta, 

 but a compound nucleus with three embryo-sacs, are as follows : — 



The central body is stated by Griffith to form at first, in Osyris, but a sUghtly-elevated 

 cone with three (or fovu") papiUse (or nuclei) at its sides. In the yoimgest specimens of 

 Santalum I examined, the placenta was highly developed as a pillar in the centre of the 

 ovary (Tab. XVII. figs. 1 & 2). The papillge might be either three points of one ovule, 

 or three nuclei with three chalazal ends blended in the centre, and the growing-up of the 

 central column, which goes on for a certain time after the embryo-sacs are distinguish- 

 able, might be regarded as a conversion of the compound ovule, or the three conjoined 

 ovules, into an anatropous structm-e, the chalazal end being at the apex of the conical 

 mass, the micropyles free and turned down next the " funiculus." The subsequent retro- 

 version of the embryo-sacs would still be anomalous, connected however in some degree, 

 through Osyris, Avicennia* and Myzodendroni (in which the embryo-sac is not extended 

 unless fertilized) with the ordinary conditions. Then the growth of the posterior ends of 

 the embryo-sacs would seem to represent a kind of chalazal structure, connecting them 

 below in a kind of central raphe with the peduncular placenta. The relative positions of 

 the remains of the nuclei and the central body, and of the remains of the peduncle of the 

 placenta, in the ripe fruit, would then indicate a rupture at the umbilicus, which was 

 carried vip to near the top of one side of the seed, while the funiculus was driven outwards 

 on the same side, and almost obliterated!. 



Some degree of likelihood attaches to the explanation just given when the Samtalacece- 

 are compared with the Loranthacece, with which they appear to be nearly connected 

 through Myzodemlron (which genus is nearer the former than the latter family as regards 

 ovulary structure §). In the Loranthacece the supposed compound, triple ovule, being 

 atropous instead of anatropous, would natm-ally be still more completely combined into 

 one piece ; it would here be almost a question of words whether there were confluent 

 nuclei or one nucleus with three parallel embryo -sacs. Then the phenomena observed in 

 Loranthus might afford a still farther confirmation, as indicating analogy with the Coniferce, 

 in which the existence of a number of (secondary) embryo-sacs is the rule. 



These points deserve fm^ther attention, and can only be elucidated by the study of the 

 development in more of the genera of these remarkable families. I should not omit to 

 mention here the observations of DeCaisne on Thesium || , which I have not yet repeated, 

 but which agree essentially with the statements respecting Santalum made by Griffith 

 and myself. 



The reason which perhaps most of all induced me to present these observations to the 

 notice of the Society, is the remarkable analogy which is shown to exist between the 

 phenomena of fecundation above described, and those which have recently been demon- 



* Griffith, Linn. Trans, xx. p. 1. 



t Hofmeister, in Grisebach, iib. Philippi und Lechler's Pflanzeusamml. Abhantll. Getting. Gesellsch. 1854. 

 X In Santalum no vascular cords can be distinguished in the conical placenta ; in Avicennia, according to Griffith, 

 {I. c.) the vascular cord reaches nearly to the base of the embryo-sac, so that the chalazal end of the ovule is marked. 

 § R. Brown, Linn. Trans, xix. p. 231 ; Hofmeister, /. c. 

 II .\nn. des Sciences nat. 2"' sir. xiii. p. 300. 



