THE ORCHID REVIEW. 103 
FERTILISATION OF DISA GRANDIFLORA. 
SoME recent information throws an interesting light on the fertilisation of 
the beautiful Disa grandiflora, which was formerly obscure. In 1864 
Mr. Rowland Trimen, F.R.S., published a note on the subject (Journ. Linn, 
Soc. VII., p. 144), in which he observes:—‘‘ When I examined the plants, 
most of the flowers were partially withered; but in the greater number, 
even in those quite withered, both pollinia were still in their cases; in not 
one instance had both been removed, but in several flowers one had been 
carried away. In some of the withered flowers the pollinia protruded from 
the anther case ; and in a few instances the upper sepal, in curling inwards, 
had touched the disc, and had drawn out the pollinium; but I saw no case 
in which the pollen-grains had thus reached the stigma. Considering how 
well-stored the nectary is with honey, it is surprising that the flowers are 
not more regularly visited ; but as the nectar fills the lower part alone of 
the nectary, only insects with a long proboscis could reach it; and perhaps 
the larger moths are rare at the elevation at which this plant grows. The 
remarkably brilliant colours, however, of the flower probably indicate that 
it is attractive to some day-flying Hymenopterous or Lepidopterous insect. 
However this may be, the infrequency with which the pollen-masses are 
removed offers a nearly parallel case to that described by Mr. Darwin, of the 
extremely imperfect fertilisation of the Ophrys muscifera in England.” 
To this Mr. Bolus added (Orch. of Cape Peninsula, p. 88):—‘ Mr. Trimen 
has since informed me that he had never found any trace of insect agency. 
I have never seen a matured seed-vessel, nor been able to detect any insect 
employed in its fertilisation. On its native range of mountains it has a 
wide range of altitude, grows vigorously in dense masses, or at least several 
together, being apparently propagated exclusively by the formation of new 
tubers, and isolated plants (such as might be expected if it seeded freely) 
are rarely to be seen. Considering the brilliant colour of the flowers these 
facts are remarkable, and seem to point to the extinction of the insect by 
which this insect was originally fertilised. If we seek still further for the 
cause of such extinction, the suggestion might be hazarded that it may be 
due to repeated bush-fires, which some observers think may have been 
prevalent for a period long prior to the advent of Europeans in 
South Africa, and have played a very important part in the modification 
both of plants and animals in this region.” 
These observations were not very conclusive, and, as Mr. Bolus himself 
remarked, show little more than our ignorance. __It is the more interesting, 
therefore, to learn from him that instances have since been observed of the 
visits of a butterfly (Menaris tulbaghica) to the flowers, and the consequent 
removal of the pollinia; and, although the fertilisation of this Orchid is rare, 
