ORCHIDS. 95 
right portion of the column ends in a single anther, The 
pollen, instead: of lying in two or more cells or cavities as 
dust, is united into masses called pollinia in all orchids. In 
| this species there 
are 4 pollinia in 
the anther ; each 
is in the form of 
an oblong flattish 
Big. 184, Colamn Hig. 185. Pollinia 
yy est of Dendrobium, of Dendrobiwn, 
Fig. 183. Column of Den- fron {i View withdrawn ona 
drobiuwm, seen from the (mag.). needle (mag.). 
side (mag.). 
plate, and these unite in pairs to form a strap-shaped caudicle, 
or thong, by which they are joined in front to a viscid gland 
on the rostellum. This rosteilum is the beak, or point, of 
the column, which projects out in front of the anther. Below 
it, and forming a nearly square viscid depression or pit in the 
front of the column, facing the labellum, is the sfigma, which 
is imperfectly 2-lobed. The sides of the column near the top 
are slightly inflated in a wing-like manner. 
The flowers usually hang in such a manner that the 
labellum is on the lower side, so that if an insect alight on it 
it hangs down and exposes the nectar-gland. As the insect 
moves forward to sip the nectar, the elasticity of the labellum 
tends to press it against the column. In moving back out of 
the flower it brushes the viscid rostellum with the top or back 
of its head, and in this way removes usually all four of the 
pollinia, which, however, by the mode in which they are with- 
drawn from the anther, are pulled forward a little on the 
insect’s head. In visiting the next flower these pollinia are 
in such a position by this depressing action that, as the insect 
advances its head, they miss the rostellum, but are thrust 
below it into the stigmatic cavity. It will be easily seen that 
seli-fertilisation of these flowers is absolutely impossible in a 
State of nature. 
The evary matures into a capsule, which dehisces by 3 
placentiferous valves ; these separate away above and below, 
leaving the midribs of the carpels standing. The seeds are 
very minute and light, in appearance like very fine sawdust, 
and are readily dispersed by the wind. Owing to their size, 
their structure is only made out with great difficulty. They 
have a very loose, reticulated testa, enclosing a solid, appa- 
rently structureless embryo. 
