2(J8 SECRETION OF NECTAR. Ciiav. IX. 



one minute and a half ; in an Odontogiossimi in two 

 minutes; and in neither of these Orchids was there 

 any free nectar. On the other hand, in Aagroecum 

 sesquipedale, which has free nectar stored within the 

 lower end of the nectary, the disc of the pollinium, 

 when removed from the plant and with its surface 

 disturbed, was strongly adhesive after forty-eight 

 hours. 



Sarcanthus teritifolius offers a more curious case. 

 The disc quite lost its viscidity and set hard in less 

 than three minutes. Hence it might have been ex- 

 pected that no fluid would have been found in the 

 nectary, but only in the intercellular spaces; never- 

 theless there was fluid in both places, so that here v.e 

 have both conditions combined in the same flower. It 

 is probable that insects would sometimes rapidly suck 

 the free nectar and neglect that between the two 

 €oats; but even in this case I strongly suspect that 

 they would be delayed by a totally different means 

 in sucking the free nectar, so as to allow the viscid 

 matter to set hard. In this plant, the labellum with 

 its nectary is an extraordinary organ. I wished to 

 have had a drawing made of its structure ; but found 

 tliat it was as hopeless as to give a drawing of the 

 wards of a complicated lock. Even the skilful Bauer, 

 with numerous figures and sections on a larue scale, 

 hardly makes the structure intelligible. So com- 

 plicated is the passage, that I failed in repeated 

 attempts to pass a bristle from the outside of the 

 flower into the nectary ; or in a reversed direction 

 from the cut-ofi" end of the nectary to the outside. No 

 doubt an insect with a voluntarily flexible proboscis 

 could pass it through the passages, and thus reach 

 the nectar ; but in effect in g this, some delay would 

 be caused ; and time would be thus allowed for the 



