46 OBSERVATIONS ON THE FERTILIZATION OF DISA MACRANTHA. 
= a eal 
In the normal position of the open flower the anther lies back, - 
behind and above the stigma, nearly at right angles to the stig- 
matic surface. The caudicles rise upwards and forwards from 
the anther-case to their junction with the viscid disks. These 
are placed parallel to each other in the clefts of the lofty turret- 
like rostellum perpendicularly to, a little behind, and consider- 
ably above the stigma. 
The disks are exceedingly viscid, and take some time to harden. 
On withdrawal the large heavy pollinium hangs down by its own 
weight, and freely dangles in the air, suspended by the long and 
flexible caudicle. 
The plants generally grow in open gullies at the base of the 
* Kagaberg." I have, however, met with them on the mountain 
itself. They are generally surrounded by high grasses and her- 
baceous plants, and seem to prefer moderately sheltered and 
moist situations. 
Nothing can be simpler than the fertilization of the flower. 
The brillant colouring, the heavy perfume, the conspicuous 
size of the plant and flowers, are sufficient to attraet both by day 
and night flying insects; and although I have never detected any 
in the act of fertilizing, nor seen any with the pollinia attached, 
I feel assured it must be frequently visited. 
The plants bear abundance of seed—in which respect they 
differ from Disa cornuta, so far as my observations go, and from 
Disa grandiflora, according to Mr. Trimen (vide Journ. Linn. 
Soc. vol. vii. no. 27, p. 144). 
There is one point, however, to which I would wish to draw 
attention, viz. £o the frequency of self-fertilization in this species. 
A very slight jerk, when the flower is fully expanded, suffices to 
eject the pollinia from their widely open anther-cases, and to bring 
them into contact with the stigma. This in nature is not un- 
seldom the case, as I have repeatedly found many flowers thus 
fertilized. Iam inclined also to think that an insect withdrawing 
the pollinia, attached as they must be to the lower portion of it$ 
body, would probably also fertilize the same flower. 
The anther in this species is supine; in D. cornuta it lies still 
further back ; but in D. grandiflora it assumes a position slightly 
more erect. i ' 
In the bud the anther is nearly quite erect, and the rostellum 
projects right in front of and over the stigma. 
Both D. grandiflora and cornuta are comparatively sterile, 
