INTRODUCTION. 85 
flowers have been supposed to be the most attractive colours to 
insects; yellow and green less so; while white flowers are probably 
most visited by night-moths. It is not always easy to define 
accurately and briefly the colours of Cape Orchids, since they are 
often variously combined in the same flower. I have endeavoured to 
arrange them in groups as to their predominant colours, with the 
following results :— 
GEOR ie eiic cesses 9 species. 
Weollow | .........600......00ne 3, en 
MSPOWT ci ics occ ssc 5 eee. ee Bae 
PGO 22s Ai Sivcisccd ss eass. ee ae 
Blue and blue-purple ......... 2”), 
WRG 20 .5...652. 00.0.0... io)", 
Liparis has green flowers; Eulophia, brown, yellow, and white ; 
Bartholina, purple and white; Satyrium, all colours named above, 
except blue; Disa, all the colours named above; Disperis, red, yellow, 
and green; Corycium, yellow and white; Pterygodium, yellow and 
purple; Ceratandra, yellow, white, and red. 
With respect to the odours exhaled by the different species, it is 
noticeable that, speaking generally, those of red hues are the least 
fragrant; those with white flowers most so. The scent of some 
(chiefly species with yellow flowers, as Corycium orobanchoides, 
Pterygodiwn catholicum, &c.) is often heavy and unpleasant. 
VIIL.—Ferrinisation oF THE FLOWERS. 
The fact that a vast number of Orchids, if not the great majority 
of species, are fertilised by insect agency only, has already been 
mentioned. I have not observed the actual process in any Peninsular 
species, although it is certain that a large number are so fertilised. 
M. Peringuey, an able and experienced entomologist, who has resided 
several years in Cape Town, has informed me that he has never 
captured or seen any insect with the pollinia of an orchid adhering to 
it. I add, however, a few notes made upon specimens gathered, which 
show evidences of the removal of pollinia by insects, or of fertilised 
capsules. 
Bartholina pectinata.—The method of fertilisation of this species is 
very similar to that of Orchis mascula, as described by Darwin, and is 
a useful illustration for beginners in the study of Cape Orchids. The 
process may be readily understood if a fine-pointed pencil be introduced 
into the throat of the flower, and then withdrawn. It will be observed 
that the pollinia adhere by the viscid glands, and stand upright upon 
the pencil-point, making a right angle with it, exactly as they would 
do upon the head of any insect seeking to rifle the flower of its honey. 
