244 THE FERTILISATION OF FLOWERS. [PART IIT. 
time they bend in towards the centre of the flower, but after 
dehiscing they again move outwards. This peculiarity was known 
to Treviranus, but was explained by him as aiding self-fertilisation 
(742). ‘On the contrary it aids cross-fertilisation, by causing the 
insect-visitors to come in contact with the pollen-dusted anthers. 
In most of the species of Saxifraga which I have investigated 
(S. rotundifolia, L., S. stellaris, L., S. aspera, DC., 8S. bryoides, 
L. = S. aspera, var. B, S. aizoides, L., 8S. Aizodn, Jacq., S. coesia, L., 
Fic. 79.—Sawifraga Seguieri, Spreng. 
A.—Flower, in first (female) stage, seen obliquely from above. The stigmas are mature. Anthers, 
. 
petals, and sepals are still far from their full size. 3 5 
B.—Flower, at commencement of second (male) stage. The stigmas are shrivelled at the tip 
the anthers are all still closed. (a’ dehisced while the drawing was being made.) ; 
C.—Flower, at the beginning of the second half of the second (male) stage. The five oute 
anthers are already empty; of the five inner, a has dehisced, and a? is in the act of dehiscing 
The stigmas are entirely shrivelled up. . 
D.—A still older flower. Of the five inner anthers three are still covered with pollen, one i 
still closed. 
E.—Section of flower in second stage. (x 7.) 
S. exarata, Vill., S. stenopetala, Gaud.), the stigma only ripens ¢ 
the anthers have withered. Engler thought that this was the es 
in all the species, but S. oppositifolia, L., and also S. tridactyli 
L., a lowland species, are only feebly proterandrous in certe 
localities, and in others are feebly proterogynous ; and three species, 
S. androsacea, I, S. muscoides, Wulf., and S. Seguieri, Spr., I have: 
found tio be everywhere distinctly proterogynous, only the first of the 
three being able in case of need to fertilise itself. 
As in diecious entomophilous plants the male flowers 
