Chap. IV. SPIEANTHES AUTUMNALIS. 109 



dition of the flowers after they have been open for a 

 day or two, and have been visited by insects. The 

 fork soon withers. 



Whilst the flower is in bud, the back of the boat- 

 formed disc is covered with a layer of large rounded 

 cells, so that the disc does not strictly form the exterior 

 surface of the back of the rostellum. These cells 

 contain slightly viscid matter : they remain unaltered 

 (as may be seen at fig. E) towards the upper end of 

 the disc, but at the point where the poUinia are at- 

 tached they disappear. Therefore I at one time con- 

 cluded that the viscid matter contained in these cells, 

 when they burst, serve to fasten the threads of the 

 poUinia to the disc ; but, as in several other' genera, 

 in which a similar attachment has to be effected, I 

 could see no trace of such cells, this view may be 

 erroneous. 



The stigma lies beneath the rostellum, and projects 

 with a sloping surface, as may be seen at B in the 

 side-view: its lower margin is rounded and fringed 

 with hairs. On each side a membrane (d, B) extends 

 from the edges of the stigma to the filament of the 

 anther, thus forming a membranous cup or clinandrum, 

 in which the lower ends of the pollen-masses lie safely 

 protected. 



Each pollinium consists of two leaves of pollen, 

 quite disconnected at their lower and upper ends, but 

 united for about half their length in the middle by 

 elastic threads. A very slight modification would 

 convert the two poUinia into four distinct masses, as 

 occurs in the genus Malaxis and in many foreign 

 Orchids. Each leaf consists of a double layer of 

 pollen-grains, joined by fours together, and these 

 united by elastic threads, which are more numerous 

 along the edges of the leaves, and converge at the 



