52 THE FERTILISATION OF FLOWERS. {CHAP. 
open, as in fig. 63. From the inverted position of 
the flower self-fertilisation is as difficult here as in 
Fuchsia (p. 36). 
Exigencies of space prevent us doing more, under 
this head, than calling attention to a very beautiful 
and interesting order of plants, to a description of the 
fertilisation of which Mr, Darwin has devoted a large 
Fic. 64. 
volume. We allude to the Orchids, about the strange 
forms of which we may have something to say ina 
future chapter. Certainly no more remarkable in- 
stance of the adaptation of plants to their insect- 
fertilisers could be found outside this group of plants. 
In the Common Purple Orchis the pollen is produced 
in two club-shaped masses, the po//inza, as in figs. 64, 
65, and 66. The stigma is a viscid disc below the 
pollinia. Part of the corolla forms a platform on 
which the insects alight (/abe//um), and it is continued 
downwards and backwards as a tube (mectary), in 
which the honey is secreted. To get at the honey 
