OP SANTALUM ALBUM. 71 



conical, or rather spindle-shaped pillar, the free placenta of authors, arising from the 

 centre of the base ; the internal surface of the walls of the ovary are closely applied to 

 the placenta, without however contracting any adherence either at the sides or above. 

 In the youngest buds I examined (Tab. XVII. fig. 1) I foimd the central placenta with 

 three cellular papiUse projecting downwards from the thickest portion, near the base, that 

 part of the placenta below their origin being narrowed into a kind of peduncle (Tab. XVII. 

 fig. 2). These papillae, of cylindrical or slightly conical form, AAdth blunt ends, pointed 

 downward and a little outwards ; they were composed of tolerably compact cellular tissue, 

 and according to the view commonly taken of the structure of this genus, they are the 

 nuclei of thi'ce ovtiles (fig. 2. a, a). In the yoimgest specimens examined, no trace of an 

 embryo-sac could be seen, but a lighter streak (as seen by transmitted light) soon appears 

 in the axis of each nucleus, indicating a cavity, and in a little farther advanced state a 

 closed tubular process was found projecting from the point of each nucleus, the free 

 extremity of a tubular embryo-sac extending internally up to the organic base of the 

 nucleus. Examined in successive stages, the tubular embryo-sac is seen to extend down- 

 wards at first ; then its external (or anterior) end (organic summit) turns outwards, next 

 suddenly upwards over the side of the nucleiis ; it becomes then more and more elongated 

 until it has grown up upon the side of the placenta so far as nearly to reach its free siim- 

 mit. It lies upon the outside of the placenta in the form of a slender filamentous tube 

 (Tab. XVII. fig. 4., b). At the same time the posterior or internal end of the tube elon- 

 gates in the substance of the placenta until it makes its way nearly to the apex. These 

 phaenomena occur in aU the other (occasionally four) ovules, alike. The tubular embryo- 

 sacs contain protoplasmic matter with a few granules, but are comparatively clear as 

 contrasted with the cells of the nucleus, which are filled with dense protoplasm and 

 (starch-) granules. 



The next stage is the formation of a bulbous enlargement of the embryo-sac at the 

 point where it turns up to rise over the placenta (Tab. XVII. fig. 6). The free points of 

 the tubular sacs also contract a slight adherence to the side of the placenta near the sum- 

 mit, remaining free however in the greater part of theu' length, although closely appUed 

 to the side of the column. The protoplasmic contents next begin to increase in quantity 

 and consistence, especially at the apex and below the bulb. A seijtum is soon afterwards 

 formed at the bottom of the bulb, which, at first flat, becomes convex (looking upwards), 

 and finally appears as an inner bulb projecting up into the cavity of the primary bulb 

 (Tab. XVII. fig. 7). The septum divides the embryo-sac into two distinct portions ; I have 

 never discovered any cell-formation Avithin the cavity beliind (or below) the septum, either 

 externally or internally to the nucleus. The only change this posterior (or organically 

 inferior) part of the embryo-sac vmdergoes, is a tubular ramification in the substance of 

 the placenta, to be described presently. 



About the time of the formation of the septum just referred to, which is about the 

 period of the opening of the flower, the apex of the embryo-sac becomes a little swollen 

 (clavate), and protoplasm accumulates on it. Soon after this, before any pollen-tubes 

 reach the placenta, from the stigma, a granular cell-nucleus, becoming gradually better 

 defined, makes its appeai'auce in the protoplasm of the clavate end, not quite at the extre- 



