168 VANDE^E. Chap. VL 



almost withered ones, for I imagined that the mouth 

 of the chamber might be of larger size at some period 

 of growth ; but the difficulty of insertion remained 

 the same. Now when we observe that the viscid disc 

 is extraordinarily small, and consequently its power of 

 attachment not so firm as witli Orchids havine- a lar^e 

 disc, and that the pedicel is very long and thin, it 

 would seem almost indispensable that the stigmatic 

 chamber should be unusually large for the easy 

 insertion of the pollinium, instead of being much con- 

 tracted. Moreover, the stigmatic surface, as Dr. Hooker 

 has likewise observed, is singularly little adhesive ! 



The flowers when ready for fertilisation do not 

 secrete nectar * but this is no difficulty, for as Dr. 

 Criiger has seen humble-bees gnawing the projections 

 on the labellum of the closely allied Gongora maculata, 

 there can be little doubt that the distal cup-shaped 

 part of the labellum of Acropera offers a similar at- 

 traction to insects. After numberless trials in manv 

 ways, I have found that the poUinia can be removed 

 with certainty only by pushing the rostellum a little 

 upwards with a camel-hair brush, held in such a 

 position that the tip slides along the under side of the 

 rostellum, so as to brush off the little viscid cap on its 

 extremity, into which the hairs enter and are glued 

 fast. I further find that if the brush with a pollinium 

 thus attached to its tip is pushed into and then with- 

 drawn from the stigmatic cavity, the mouth of which 

 is furnished with a sharp ridge, the end of the pedicel 



* I\Tr. Scott lias observed that at no other time couM he finil a 



after the flowers of Acroi)era and trace of nectar. Tliis exmlation 



of two species in the allied genus can, tliereforc, be of no use to tlie 



of Oongora have been fertilised, plant with respect to its fertili- 



an abundance of nectar exudes sation. and must be viewed as an 



from the front of the column ; but excretion. 



