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 



o 



FIG. 64. 



volume. We allude to the Orchids, about the strange 

 forms of which we may have something to say in a 

 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 pollinia, 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 (labellum), and it is continued 

 downwards and backwards as a tube (nectary), in 

 which the honey is secreted. To get at the honey 



