182 MR. T. H. CORRY ON ASCLEPIAS CORNUTI. 
appearance, if it occurred only in a single section, would indicate merely the upper 
termination of the staminal column in this region ; but, since it occurs in several sections 
succeeding one another, it shows somewhat more than this. For in the median line of 
the alar furrow, in consequence of the mode in which the upper extremity of the staminal 
column terminates superiorly on either side, a very shallow notch is found to be left in 
the column when, after the partial removal of the ale by section, it is looked at from 
the front. This notch is opposite to the completely open canal of the alar chamber. 
Viewed from above for its whole length, it forms a very short and shallow radial furrow 
(r, fig. 11). Тһе style-table is found, on examination, to be closely applied by the 
whole circumference of its base to the superior edge of the staminal column formed by 
the 5 united filaments, except at 5 points. Each of these points corresponds in position 
to one of the 5 alar fissures, and is due to the presence of one of the short radial furrows, 
formed in the manner just described. The appearance presented by the upper ends of 
the cells forming the side of the short radial furrow was accurately figured by Adolphe 
Brongniart *, although both he and Robert Brown seem to have been altogether 
ignorant of the existence of the five radial furrows themselves, which I may remark, in 
passing, it requires very careful examination and manipulation to show clearly, especially 
in longitudinal sections. At the 5 points above mentioned, which are directly opposite 
the 5 alar fissures, a slight means of communication exists between the parts which are 
enclosed in the interior of the staminal tube and the exterior of the flower (m, fig. 18), 
the object of which will be considered at length hereafter. Schleiden alone seems to 
have had some idea of the 5 furrows, though his account is vague. He remarks that 
“immediately below the 5 (alar) grooves 5 points remain without acquiring a perfect 
epidermis beneath, while 5 cords of conducting tissue are formed from these 5 points 
into the canals of the 2 styles" +. His * 5 points" evidently refer to the external begin- 
nings of the conducting tissue (stig., fig. 11; e, fig. 13). 
The form of each of the pollinia is more or less obovate. The pollinium is further 
flattened and compressed, appearing elliptical in transverse section, but with one edge 
slightly more convex than the other (pol., fig. 19). 
The contents of the anther-cells being fully mature, each of them, immediately prior 
to the expansion of the flower, opens internally. This is effected by almost the whole 
of the thin-walled parenehymatous tissue which forms the substance of the anther, 
together with the remains of the two tapetal membranes, becoming broken down. The 
change also affects the upper portion of the epidermis on the internal side of the anther, 
which is never cuticularized. The disintegration appears to take place from above down- 
wards, commencing first at the apex of each of the cells, and gradually proceeding 
downwards. The apices of the pollinia are thus exposed first, and on their internal side. 
Immediately on its exposure the apex comes into contact with the lower or inferior free 
ends of one of the corpuscular appendages, which is still in a semiliquid condition, and 
extends slightly beyond its furrow. The viscid end of the appendage flattens itself 
* «Quelques Observations sur la maniére dont s'opére la fécondation dans les Asclépiadées,” Ann. des Se. Nat. 
vol. xxiv. 1831, pl. xiv. fig. 5. 
+ ‘Principles of Scientific Botany,’ ed. iii. 1849, pp. 381, 382. 
