212° THE FERTILISATION OF FLOWERS. [parr it. 
up again, so that while the stigma and style-brush return | 
within the carina, great part of the pollen is swept off and remains — 
outside, The ends of the filaments, lying in the base of the 
conical point of the carina, are slightly swollen even in the bud 
(7, fig. 71), but after the anthers have dehisced they enlarge more 
(9), and so press the pollen forward more effectively than in the — 
case of Lathyrus pratensis. They press the pollen in the base of | 
Fig. 71.—Pisum sativum, Li. > 
1 —Flower, after removal of left ala. i 
2.—Inner view of left ala. ; 
3.—Antcrior view of vexillum. 
4,—Carina, from above, enlarged. 
5.—Ditto, inclosed by the ale. 
6.—Basal half of left ala; outer view. 
7.— Essential organs from a bud (x 383). 
8.— Anterior part of style, from within (x 7). 
9.—One stamen of the flower. 
(For letters, see the text.) 
the cone forward to its apex, so that the style-brush on returni 
within the carina becomes covered again with pollen, and so : 
new portion of pollen is forced out at each depression of 
carina. Thus the flower of the Pea combines the brush-mechanis 
with the piston-mechanism. 
The force needed to depress the carina is both absolutely 
relatively greater than in Lathyrus pratensis, since the style-b 
