248 
A TEXT-BOOK OF BOTANY 
the style sends out as a roof to the pocket (Fig. 242). 
With such an arrangement it would seem impossible for the 
pollen to reach the stigma unaided. The nectar is in a 
Fic. 243.—Flower of rein orchis: A, com- 
plete flower, showing three broad se- 
pals, three narrower petals (one of 
which forms the long lip and the much 
longer spur), two pollen sacs, between 
which extends the concave stigmatic 
surface (at the bottom of which the 
opening to the tube is seen); B, more 
enlarged view of pollen sacs, stigmatic 
surface, and buttons; C, a pollinium 
removed; D, a button enlarged.—Af- 
ter GRAY. 
little pit at the bottom of 
the pocket. As the insect 
crowds its way into the nar- 
rowing pocket, its body is 
dusted by the pollen; and 
when it visits the next 
flower, and pushes aside the 
stigmatic shelf, it is likely 
to deposit upon it some of 
the pollen previously re- 
ceived. 
In the orchids, remark- 
able for their strange and 
beautiful flowers, the story 
of pollination is still more 
complicated. There are 
usually two pollen sacs, and 
the pollen grains are not 
dry and powdery, but cling 
together in a mass (pollin- 
zum), which must be pulled 
out bodily. An illustration 
of a common method of 
pollination may be obtained 
from the common rein or- 
chis (Fig. 243). Each of the 
two pollen masses termi- 
nates in a sticky disk or 
button; and between them 
extends the concave stigmatic surface, at the bottom of 
which is the opening into the long tube-like spur in the 
bottom of which the nectar is found. Such a flower is 
