Chap. IV. LISTEEA OVATA. 115 



of Australia, has been described and figured by Mr. 

 Fitzgerald.* The flowers are arranged on the spike 

 in the same manner as in 8. autumnalis; and the 

 labellum with two glands at its base closely resembles 

 that of our species. It is therefore an extraordinary 

 fact that Mr. Fitzgerald could not detect even in the 

 bud any trace of a rostellum or of viscid matter. He 

 states that the poUinia touch the upper edge of the 

 stigma, and fertilise it at an early age. Protecting a 

 plant from the access of insects by a bell-glass made 

 no difference in its fertility ; and Mr. Fitzgerald, 

 though he examined many flowers, never noticed the 

 slightest derangement of the poUinia, or any pollen 

 on the surfaces of the stigmas. Here then we have 

 a species which fertilises itself as regularly as does 

 Ophrys apifera. It would, however, be desirable to 

 ascertain whether insects ever visit the flowers, which 

 it may be presumed secrete nectar, as glands are 

 present ; and any such insects should be examined, so 

 as to make certain that pollen does not adhere to some 

 part of their bodies. 



Listera ovata, or Tway-llade. — This Orchid is one 

 of the most remarkable in the whole order. The 

 structure and action of the rostellum has been the 

 subject of a valuable paper in the 'Philosophical 

 Transactions,' by Dr. Hooker,t who has described 

 minutely and of course correctly its curious structure ; 

 he did not, however, attend to the part which insects 

 play in the fertilisation of the flowers. C. K. Sprengel 

 well knew the importance of insect-agency, but he 

 misunderstood both the structure and the action of 

 the rostellum. 



The rostellum is of large size, thin, or foliaceous, 



• ' Australian Orchids,' part ii. t ' PliilnsopliiLal Transactions,' 



187C. ISoi, p. 259. 



