128 
THE FLOWERING PLANT. 
of the way, so to speak. An upper stamen would be so blocked 
up by it as to be of little use. 
Fig. 51.—Structure of Pansy [from Sachs]. 
All but A. magnified. A. longitudinal 
section of flower. B. ovary and anthers, 
the former fertilized and swollen; the 
‘filaments have been broken off and the 
anthers carried forwards by growth of 
ovary. C. stigma, style, and top of ovary. 
D. transverse section of ovary. E. trans- 
verse section of young anther, showing 
two pollen-sacs in each lobe and con- 
nective uniting lobes; v. bracteole ; J, U’. 
sepals; ls. appendage of sepal; ¢, ¢, ©. 
petals; es. spur of lower petal; a. anthers ; 
f. filaments; fs. nectar-excreting appen- 
dages of lower stamens; n. stigma; 0. 
opening of stigma ; lp. lip of stigma; gv. 
style; fK. top of ovary; sp. placentas ; 
sk. ovules. 
Take, for example, foxglove. 
The lower lip forms a landing- 
stage from which an insect can 
creep into the bell. Only a large 
form like the humble-bee is use- 
ful, as the size of the corolla pre- 
vents others from touching the 
stigma and anthers. ‘The flower 
is to some extent proterandrous, 
and, as in so many cases, the 
stigma projects beyond the sta- 
mens. ‘The didynamous con- 
dition is well adapted for dis- 
playing the anther lobes, which 
are at first transverse, but after- 
wards move into a vertical posi- 
tion. 
The personate corollas of toad- 
flax and snapdragon can only be 
forced open by bees. In the 
latter case humble-bees are 
almost the sole visitors, as others 
are not strong enough to press 
down the lower lip. 
Musk is particularly interest- 
ing among lipped forms, from 
the fact that the stigma is in 
the form of two flattened sensz- 
tive (especially in the large 
scentless musk) lobes, which 
close on contact. Pollen can 
thus be deposited in it by an 
arriving, but not by a departing 
uest. 
White dead nettle presents an 
arrangement common in labiate 
flowers. The lower lip forms a 
convenient landing-stage; the 
upper one not only protects the 
stamens and pistil, but keeps 
them pressed firmly down. A 
visitor settling on the lower lip touches first the forked stigma, 
' which hangs down a little, and then the anthers of the didy- 
