FERTILIZATION OF PHACELIA. 57 
perhaps, for self-fertilization. It is largely visited by bees 
(collecting honey and pollen) and Syrphide (for pollen). Only 
the bees are of service to the flower. The flies alight on the corolla 
and collect pollen from one anther at a time, without touching 
the stigmas. Bees alight sometimes on the corolla, touching 
styles and stamens with their backs as they reach for the honey, 
sometimes on the stamens, crushing them all up together with 
the styles, and probably causing self- as much as cross-fertiliza- 
tion. After visits of this second type, large quantities of pollen 
are usually found on the stigmas, if these are in their later 
stages. 
Self-fertilization may occur as described above, or by pollen 
falling from the anthers as the styles grow, or on the fall of the 
corolla, which carries the stamens with it, and may rub the 
anthers over the stigmas in falling. In one case observed it 
occurred by the lengthening style growing right into an anther 
and so getting covered with pollen. 
Of the flowers on plants left to themselves, about two-thirds 
only set seed. Another plant was grown under a muslin net, 
and only one flower out of 19 set seed. Very probably this one 
became self-fertilized in one of the accidental ways above referred 
to. Three flowers on another plant were fertilized in the earliest 
male stage, and then castrated and the corolla removed ; only 
one of them set seed, and this may also have been due to 
subsequent accidental fertilization. Probably therefore, as the 
microscopic examination also shows, the stigmas are not recep- 
tive in the earliest stages. 
The effect of covering with the muslin net was very striking 
as regarded the colour of the flowers; those which came out 
under its shade were of a much paler blue than those growing 
in the open sunlight. 
P. Whitlavia (Whitlavia grandiflora, Harvey *).—This plant, 
belonging to the same subgenus as the last, closely resembles it. 
The campanulate corolla is somewhat larger, the total depth and 
total width being each about 24 to 27 mm. The tube is 10 mm. 
wide at the base, narrowing to 8 mm. in the throat. The colour 
is a dull purplish blue. There are no longitudinal furrows in 
the tube of the corolla, nor coloured honey-guides. It is covered 
with short downy hairs, and the size remains almost constant 
whilst the flower is open. The stamens stand closely round the 
* Bot. Mag. t. 4813. 
