SELF-FERTILIZATION IN TROPICAL ORCHIDS. 539 



which I hare examined thousands of flowers : scarcely one in 

 eighty ever sets a seed-capsule. 



Calqnthe veratrifolia produces quite a dense head of elegant 

 white flowers ; but the number of these that become fertilized 

 is in enormous disproportion to those that fall off barren. 

 I have examined plants in numerous situations, on heights 

 amid the dense forest as well as in open places. I have studied 

 them low down, both in sun and in shade, and I have in- 

 variably found that a very small proportion of flowers produce 

 fruit. G-enerally the pollinia are found in the anther after the 

 fall of the flower ; but they are often absent without any pollen 

 being left in return on the stigma. 



In five different plants (taken at random from my note-book), 

 out of 360 flowers, 109 were withered with intact anthers, or had 

 lost their pollinia and were unfertilized ; 215 had fallen off, 6 

 only had produced capsules. 



Mr. Darwin, in his ' Fertilization of Orchids,' ed. ii. p. 290, 

 enumerates thirteen instances of self-fertilization as coming under 

 his observation — in Ophrys apifera, in Cephalanthera grandiflora, 

 Habenaria intacta, H. tridentata, S. hyperborea, Spiranthes am- 

 tralis, Neottia Nidus-avis, Disa macrantha, Ejpipactis viridiflora, 

 two Thelymitras, an Epidendrum, and two or three Dendrobia. In 

 the additional instances which I am able to adduce, some will be 

 found fertilized in a manner, I believe, never hitherto described. 

 Phaius is an exceedingly handsome and attractive genus of 

 Orchids, growing in open and sunny places, throwing up from 

 the large broad radical leaves stout erect flower-stalks, from 

 l|-2 feet in height, crowded with flowers. In P. Blumei the 

 flower-buds are at first erect and white, and enclosed in their 

 bracts ; when these fall off, the bifid-tipped nectary can be seen 

 protruding from between the sepals. The pedicel of the flower 

 now begins to twist on its own axis, either to the right or to 

 the left, and continues through 180°, the flower opening in the 

 meantime. When this half-revolution has been completed, the 

 flower has become fully expanded, while the axis of the flower 

 has descended through 90° in a vertical direction, bringing the 

 labellum to a position at right angles to the flower-stalk. The 

 expanded sepals measure laterally from tip to tip 12 to 14 centi. 

 metres. Their outer surface is white, and the inner of a rich 

 chestnut-brown ; the interior of the labellum, over which the upper 

 sepal arches, is of a beautiful bright purple-magenta colour, while 



LINN. JOURN. — BOTANY, YOL. XXI. 2 R 



