Flowers 
tions of petals or sepals, or in the orchid (probably) 
of a petal and two stamens. One has simply to suppose 
that the continual loss of honey at one point of the 
petal has caused a similar extra growth of the tissue, 
which has continued to “give” until it has formed the 
long narrow spur which is curved in accordance with 
the curvature of an insect’s proboscis.* In the butter- 
cup petal one sees the beginning of the process, which 
has proceeded so far in the aconite that nothing is 
left of the petal except a spurlike nectary. 
But this involves the inheritance of an acquired 
character, which point is to be considered elsewhere 
(see p. 295). 
Wax sometimes occurs on the epidermis of leaves 
and stems, and in some orchids there is an extra 
development of wax on certain parts of the flower. 
Here it replaces honey, for bees take it to form propolis, 
and being sticky and slippery it keeps off small insect 
thieves which are not desired, 
Besides colour, perfume, and honey or wax, there are 
thousands of other interesting modifications by which 
they have been made attractive to their average insect- 
visitor, and at the least possible expense of material. 
That flowers do change in such characters as size, 
colour, number of ray florets and the like, has been 
abundantly proved by laborious arithmetical calcula- 
tion (see p. 188). Thus the spots on a certain orchid 
(Orchis morio, var. picta) were found to vary as follows. 
In the island of Majorca the majority of the flowers had 
five spots, in Belgium six, in English and Scandinavian 
specimens nine was the commonest number, whilst 
flowers from more continental places had eleven spots.!” 
Another stock subject for such arithmetical researches 
* De Vries 1° mentions these cases, but does not adopt the obvious sugges- 
tion given here. 
120 
